In
linguistics, the
grammatical aspect of a
verb defines the temporal flow (or lack thereof) in the described event or state. For example, in English, the difference between
I swim and
I am swimming is a difference of aspect.
Aspect, as discussed here, is a formal property of a language. Some languages distinguish a large number of formal aspects (see the list below), while others distinguish none at all. 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.
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 (bhava), from those where the action is considered as a completed whole (murta). This is of course the key distinction between the imperfective and perfective. Yaska applies the same distinction also for 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.