In linguistics, the grammatical aspect (sometimes called viewpoint aspect) of a verb defines the temporal flow (or lack thereof) in the described event or state. In English, for example, the past-tense sentences "I swam" and "I was swimming" differ in aspect (the first sentence is in what is called the perfective or completive aspect, and the second in what is called the imperfective or durative aspect). The related concept of tense or the temporal situation indicated by an utterance, is typically distinguished from aspect.
Aspect, as discussed here, is a formal property of a language. Some languages distinguish different aspects through overt inflections or words that serve as aspect markers, while others, such as English, have no overt marking of aspect. For example, the K'iche' language spoken in Guatemala has the inflectional prefixes k- and x- to mark incompletive and completive aspect;  Mandarin Chinese has the aspect markers -le, -zhe, and -guo to mark the perfective, durative, and experiential aspects, and also marks aspect with adverbs; and English does not have overt marking for most aspects. Even languages that do not mark aspect formally, however, can convey such distinctions by the use of adverbs, phrases, serial verb constructions or other means; for example, English can mark progressive aspect through the use of the progressive tense (adding be before a verb and affixing -ing to the end of the verb).
Grammatical aspect is distinguished from lexical aspect or aktionsart, which is an inherent feature of verbs or verb phrases and is determined by the nature of the event that the verb describes, whereas grammatical aspect is more often determined by inflectional morphology, aspect markers, or adverbs and other syntactic constructions.
Grammatical aspect may have been first dealt with in the work of the Indian linguist Yaska (ca. 7th century BCE), who distinguishes actions that are processes (bhāva), from those where the action is considered as a completed whole (mūrta). This is of course the key distinction between the imperfective and perfective. Yaska also applies this distinction between a verb and an action nominal.
The most fundamental aspectual distinction, represented in many languages, is between perfective aspect and imperfective aspect. This is the basic aspectual distinction in the Slavic languages. It semantically corresponds to the distinction between the tenses known respectively as the aorist and imperfect in Greek, the preterite and imperfect in Spanish, the simple past (passé simple) and imperfect in French, and the perfect and imperfect in Latin. Essentially, the perfective aspect refers to a single event conceived as a unit, while the imperfective aspect represents an event in the process of unfolding or a repeated or habitual event. In the past tense, the distinction often coincides with the distinction between the simple past "X-ed," as compared to the progressive "was X-ing." For example, the perfective would translate both verbs in the sentence "He raised his sword and struck the enemy." However, in the sentence "As he was striking the enemy, he was killed by an arrow," the first verb would be rendered by an imperfective, and the second by a perfective.
Aspect is a somewhat difficult concept to grasp for the speakers of most modern Indo-European languages, because they tend to conflate the concept of aspect with the concept of tense. (The two concepts are, however, mostly independent in Slavic languages and Greek.) Although English largely separates tense and aspect formally, its aspects (neutral, progressive, perfect and progressive perfect) do not correspond very closely to the distinction of perfective vs. imperfective that is common in most other languages. Furthermore, the separation of tense and aspect in English is not maintained rigidly. One instance of this is the alternation, in some forms of English, between sentences such as "Have you eaten yet?" and "Did you eat yet?". Another is in the past perfect ("I had eaten"), which sometimes represents the combination of past tense and perfect aspect ("I was full because I had already eaten"), but sometimes simply represents a past action which is anterior to another past action ("A little while after I had eaten, my friend arrived"). (The latter situation is often represented in other languages by a simple perfective tense. Formal Spanish and French use a past anterior tense in cases such as this.)
In most dialects of Ancient Greek, aspect is indicated uniquely by tense. For example, the very frequently used aorist tense, though a functional preterite tense in the indicative mood, conveys historic or 'immediate' aspect in the subjunctive and optative. The perfect tense in all moods is used solely as an aspect marker and not, ironically, as a tense, conveying the sense of a resultant state. E.g. - I see (present); - I saw (aorist); - I am in a state of having seen = I know (perfect).
Many Sino-Tibetan languages, like Mandarin, lack grammatical tense but are rich in aspect.
It is extremely important to distinguish between grammatical aspect, as described here, and lexical aspect. Lexical aspect is an inherent property of verbs or verb-complement phrases, and is not marked formally in most languages. The distinctions made as part of lexical aspect are different from those of grammatical aspect, usually relating to situation aspect rather than viewpoint aspect. Typical distinctions are between states ("I had"), activities ("I shopped"), accomplishments ("I painted a picture"), achievements ("I bought"). These distinctions are often relevant syntactically. For example, states and activities, but not usually achievements, can be used with a prepositional for-phrase describing a time duration: "I had a car for five hours", "I shopped for five hours", but not "*I bought a car for five hours". Lexical or situation aspect is sometimes called Aktionsart, especially by German and Slavic linguists. Lexical or situation aspect is marked in Athabaskan languages.
One of the factors in situation aspect is telicity. Telicity might be considered a kind of lexical aspect, except that it is typically not a property of a verb in isolation, but rather a property of an entire verb phrase. Achievements and accomplishments have telic situation aspect, while states, activities and semelfactives have atelic situation aspect.
The other factor in situation aspect is duration, which is also a property of a verb phrase. Accomplishments, states, and activities have duration, while achievements and semelfactives do not.
In some languages, aspect and time are very clearly separated, making them much more distinct to their speakers. There are a number of languages that mark aspect much more saliently than time. Prominent in this category is Chinese, which differentiates many aspects but relies exclusively on (optional) time-words to pinpoint an action with respect to time. In other language groups, for example in most modern Indo-European languages (except Slavic languages), aspect has become almost entirely conflated, in the tense system, with time.
In Russian, aspect is more salient than tense in narrative. Russian, like other Slavic languages, uses different lexical entries for the different aspects, whereas other languages mark them morphologically, and still others with auxiliaries (e.g., English).
In high Arabic (الفصحى, "al-Fusha", the clear (language)) the verb is marked for tense but not aspect, according to the indigenous tradition. The "Past Verb" (فعل ماضي, fi'l maadiy) denotes an event (حدث, hadath) completed in the past, but says nothing about the relation of this past event to present status, nor about aspect, at least not directly. For example, "وصل", wasala, "he arrived", indicates that arrival occurred in the past without saying anything about the present status of the arriver - maybe he stuck around, maybe he turned around and left, etc. - nor about the aspect of the past event except insofar as completeness can be considered aspectual. This "Past Verb" is clearly similar if not identical to the Greek Aorist, which is considered a tense but is more of an aspect marker. In the Arabic, aorist aspect is the logical consequence of past tense. By contrast, the "Verb of Similarity" (فعل المضارعة, fi'l al-mudaara'ah), so called because of its resemblance to the active participial noun, is considered to denote an event in the present or future without committing to a specific aspectual sense beyond the incompleteness implied by the tense: يضرب "yadribu", he strikes/is striking/will strike/etc. Those are the only two "tenses" in Arabic (not counting "أمر"، "amr", command, which the tradition counts as denoting future events.) At least that's the way the tradition sees it. To explicitly mark aspect, Arabic uses a variety of lexical and syntactic devices.
Contemporary Arabic dialects are another matter. One major change from al-Fusha is the use of a prefix particle (ب "bi" in most dialects) to explicitly mark progressive, continuous, or habitual aspect: بيكتب, bi-yiktib, he is now writing, writes all the time, etc.
Aspect can mark the stage of an action. The inchoative identifies that the action is soon to take place. The inceptive aspect identifies the beginning stage of an action (e.g. Esperanto uses ek-, e.g. Mi ekmanĝas, "I am beginning to eat."). Aspects of stage continue through progressive, pausative, resumptive, cessive, and terminative.
According to one prevalent account, the English tense system has only two basic tenses, present and past. No primitive future tense exists in English; the futurity of an event is expressed through the use of the auxiliary verbs "will" and "shall", by use of a present form, as in "tomorrow we go to Newark", or by some other means. Present and past, in contrast, can be expressed using direct modifications of the verb, which may be modified further by the progressive aspect (also called the continuous aspect), the perfect aspect (also called the completed aspect), or both. Each tense is named according to its combination of aspects and time. These two aspects are also referred to as BE + ING (for the first) and as HAVE +EN (for the second). Although a little unwieldy, such tags allow us to avoid the suggestion that uses of the aspect BE + ING always have a "progressive" or "continuous" meaning, which they do not.
For the present tense:
For the past tense:
(Note that, while many elementary discussions of English grammar would classify the Present Perfect as a past tense, from the standpoint of strict linguistics – and that elucidated here – it is clearly a species of the present, as we cannot say of someone now deceased that he "has eaten" or "has been eating"; the present auxiliary implies that he is in some way present (alive), even if the action denoted is completed (perfect) or partially completed (progressive perfect).)
The uses of these two aspects are quite complex. They may refer to the viewpoint of the speaker:
I was walking down the road when I met Michael Jackson's lawyer. (Speaker viewpoint in middle of action)
I have travelled widely, but I have never been to Moscow. (Speaker viewpoint at end of action)
But they can have other meanings:
You are being stupid now. (You are doing it deliberately)
You are not having chocolate with your sausages! (I forbid it)
I am having lunch with Mike tomorrow. (It is decided)
Another aspect that does survive in English, but that is no longer productive, is the frequentative, which conveys the sense of continuously repeated action; while prominent in Latin, it is omitted from most discussions of English grammar, as it suggests itself only by Scandinavian suffixes no longer heard independently from the words to which they are affixed (e.g., "blabber" for "blab", "chatter" for "chat", "dribble" for "drip", "crackle" for "crack", etc.).
Note that the aspectual systems of certain dialects of English, such as Hawaiian Creole English and African-American Vernacular English, are quite different from standard English, and often distinguish aspect at the expense of tense.
In Slavic languages there is only one type of aspectual opposition which forms two grammatical aspects: perfective and imperfective (in contrast with English which has two aspectual oppositions: perfect vs. neutral and progressive vs. nonprogressive). The aspectual distinctions exist on the lexical level - there is no unique method to form a perfective verb from a given imperfective one (or conversely). Perfective verbs may be formed by means of prefixes, changes in the root, or using a completely different root (suppletion). Note, however, that possessing a prefix does not necessarily mean that a verb is perfective.
With a few exceptions each Slavic verb is either perfective or imperfective. Most verbs form strict pairs of one perfective and one imperfective verb with generally the same meaning. However, each Slavic language contains a number of verbs which are bi-aspectual and act as both imperfective and perfective. They are mainly borrowings from non-Slavic languages, but some native verbs also belong to this group. As opposed to them, mono-aspectual verbs are mainly native. There are mono-aspectual imperfective verbs without perfective equivalents (among others, verbs with the meaning 'to be' and 'to have') as well as perfective verbs without imperfective equivalents (for instance, verbs with the meaning 'become ...', e.g. 'to become paralyzed', etc.).
The perfective aspect allows the speaker to describe the action as finished, completed, finished in the natural way. The imperfective aspect does not present the action as finished, but rather as pending or ongoing.
An example is the verb 'to eat' in the Serbo-Croatian language. The verb translates either as jesti (imperfective) or pojesti (perfective). Now, both aspects could be used in the same tense of Serbian. For example (omitting, for simplicity, feminine forms like jela):
|Ja sam jeo/ Ja сaм јеo||rowspan=2||past||imperfective|
|Ja sam pojeo/ Ja сaм појеo||perfective|
|Ja sam bio jeo/ Ja сaм био jeo||rowspan=2||pluperfect||imperfective|
|Ja sam bio pojeo/ Ja сaм био појеo||perfective|
|Ja ću jesti/ Ja ћy jecти||rowspan=2||future||imperfective|
|Ja ću pojesti/ Ja ћy пojecти||perfective|
Ja sam pojeo signals that the action was completed. Its meaning can be given as "I ate (something) and I finished eating (it)"; or "I ate (something) up".
Ja sam jeo signals that the action took place (at a specified moment, or in the course of one's life, or every day, etc.); it may mean "I was eating", "I ate" or "I have been eating".
The following examples are from Polish.
Imperfective verbs mean:
Perfective verbs mean past or future, but not present activities – an activity which is happening now cannot be ended, so it cannot be perfective. Perfective verbs mean:
Most simple Polish verbs are imperfective (the same in other Slavic languages), ex. iść 'to walk, to go', nieść 'to carry', pisać 'to write'. But there are also few simple perfective verbs, ex. dać 'to give', siąść 'to sit down'. There exist many perfective verbs with suffixes and without prefixes, ex. krzyknąć 'to shout', kupić 'to buy' (cf. the imperfective kupować with a different suffix).
Numerous perfective verbs are formed from simple imperfectives by prefixation. To create the perfective counterpart, verbs use various prefixes without any clear rules. The actual prefix can even depend on a dialect or special meaning, ex. the perfective counterpart to malować is pomalować when it means 'to paint a wall; to fill with a color', or namalować when it means 'to paint a picture; to depict sth/sb'.
Besides the strict perfective equivalent, a number of other prefixed verbs may be formed from a given simple imperfective verb. They all have similar but distinct meaning. And they form, as a rule, their own imperfective equivalents by means of suffixation (attaching suffixes) or stem alternation. Example:
There is a number of verbs which form their aspectual counterparts by simultaneous prefixation and suffixation or by suppletion, ex. (the first one is imperfective) stawiać - postawić 'to set up', brać - wziąć 'to take', widzieć - zobaczyć 'to see'.
Special imperfective verbs are those which express aimless motions. They are mono-aspectual, i.e. they have no perfective equivalents. They are formed from other imperfective verbs by stem alternations or suppletion, ex. nosić 'to carry around' (from nieść), chodzić 'to walk around, to go around' (from iść 'to go, to walk'). However, when such a verb gets an aim anyway, it becomes iterative: chodzić do szkoły 'to go to school'.
Other iteratives build another group of mono-aspectual imperfective verbs. They are formed from other imperfective verbs, including the previous group: chadzać 'to walk around usually (from chodzić), jadać 'to eat usually' (from jeść 'to eat'). Both groups are not too numerous: most Polish verbs cannot form iterative counterparts.
Perfective verbs which express activities executed in many places, on many objects or by many subjects at the same time, and those which express actions or states which last some time, have no imperfective counterparts. They are formed with the prefix po- (which can have other functions as well).
States and activities which last for some time can be expressed by means of both imperfective and perfective verbs: cały dzień leżał w łóżku 'he was in bed all day long' (literally: 'he lay in bed') means nearly the same as cały dzień przeleżał w łóżku. The difference is mainly stylistic: imperfective is neutral here, while using perfective causes stronger tone of the statement.
Aspect in Slavic is a superior category in relation to tense or mood. Particularly, some verbal forms (like infinitive) cannot distinguish tense but they still distinguish aspect. Here is the list of Polish verb forms which can be formed by both imperfective and perfective verbs (such a list is similar in other Slavic languages). The example is an imperfective and a perfective Polish verb with the meaning 'to write'. All personal forms are given in third person, masculine singular:
The following may be formed only if the verb is imperfective:
One form may be created only if the verb is perfective, namely:
Finnish and Estonian, among others, have a grammatical aspect contrast of telicity between telic and atelic. Telic sentences signal that the intended goal of an action is achieved. Atelic sentences do not signal whether any such goal has been achieved. The aspect is indicated by the case of the object: accusative is telic and partitive is atelic. For example, the (implicit) purpose of shooting is to kill, such that:
Sometimes, corresponding telic and atelic forms have as little to do with each other semantically as "take" has with "take off". For example, naida means "to marry" when telic, but "to have sex with" when atelic.
Also, derivational suffixes exist for various aspects. Examples:
Italian grammar doesn't recognise explicitly verbal aspects, and focuses more on moods and tenses. Still, most mood/tense combinations (such as indicative/future) feature two aspects, called in italian grammar books tempi semplici (simple tenses) and tempi composti (compound tenses). The compound tenses are called so because they're formed by the appropriated auxiliary verb conjugated in the correspondent simple tense, and the main verb conjugated in the past participle. Simple tenses render the imperfective (sometime aorist) aspect, and compound tenses render the perfective aspect. This is a direct derivation of the way the latin language used to render both aspects and consecutio temporum. The compound tenses are generally used in subordinate clauses, with the sole exception of passato prossimo, used by most speakers in northern Italy as substitute for passato remoto.
Example (verb mangiare, to eat)
Mood: indicativo (indicative)
The difference between the imperfetto/trapassato prossimo and the passato remoto/trapassato remoto is that imperfetto renders an imperfective (continuous) past; passato remoto renders an aorist (punctual/historical) past.
Other aspects in italian are rendered with other periphrases, like inchoative (io sto per mangiare I'm about to eat, io starò per mangiare I shall be about to eat), or continuative/progressive (io sto mangiando I'm eating, io starò mangiando I shall be eating).
The terms perfective and perfect are used in an unfortunate and highly confusing fashion in different writings about linguistics. Traditional Greek grammar uses the term "perfect" to refer to a grammatical tense encoding what is variously described as a past action with present relevance or a present state resulting from a past action. (For example, "I have come to the cinema" implies both that I went to the cinema and that I am now in the cinema.) The perfect is opposed to the aorist, describing a simple past action, and the imperfect, describing an ongoing past action. From this, the aspectual nature of the perfect tense was generalized into the perfect aspect, describing a previously completed action with relevance to a particular time. Accordingly, English grammar speaks of the present perfect ("I have gone"), the past perfect or pluperfect ("I had gone"), and the future perfect ("I will have gone").
Latin, however, lacks a distinction between aorist and perfect, and for morphological reasons the single tense representing the combination of both meanings is called the "perfect". The two-way distinction here between imperfect and perfect is carried over into the terminology of various modern languages, such as the Slavic languages and the Romance languages, where a distinction between "imperfective" and "perfective" aspect corresponds to a distinction between an event viewed as ongoing or with internal structure and an event viewed as a simple whole. That is, what is called "perfective" is similar to the aspectual nature of the original Greek aorist, not the Greek perfect.
Many linguists have tried to maintain this terminology. The web site of SIL International, for example, describes the "perfective aspect" as "an aspect that expresses a temporal view of an event or state as a simple whole, apart from the consideration of the internal structure of the time in which it occurs". This has led other linguists to categorize the three-way aspectual distinction visible in Greek, English, Spanish and various other languages as a distinction between "imperfective", "perfective" and "perfect". Not surprisingly, the latter two are constantly confused, and "perfective" is often taken to be synonymous with "perfect".
'I would walk [OR: used to walk] home from work.' (past habit)