Definition - As defined by Steven Pinker: "[It is] the way an event is spread over time: whether it is instantaneous (swat a fly), continuous (run around all day), terminating (draw a circle), habitual (mows the grass every Sunday), or a timeless state (knows how to swim)."

1. As opposed to mood, which classifies verbs with respect to purpose, e.g. whether it is used in a command, a question, or a wish.

Example -
Some types of aspect are:
(1) the progressive aspect (We are doing homework)
(2) the perfective aspect (We have eaten lunch), and
(3) the inchoative aspect (They are about to eat).

Etymology -
The word — which was originally used to describe Slavonic languages — derives from the Latin aspectus, seeing or appearance (from ad, to + specare, to look).

Oxford English Dictionary -
Its first citation in its grammatical sense is from 1853:
"The aspects have not all the same number of tenses;
the imperfect aspect is used in all the three tenses;
the perfect is employed in the preterit and future,
while the iterative is met with only in the preterit."
Note: The term was originally used to describe Slavonic languages.
(C. P. Reiff Eng.-Russ. Gram. i. 86)

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