Meaning of “imperfect” - Learner’s Dictionary

imperfect

noun us uk /ɪmˈpɜːfɪkt/ also the imperfect tense, uk us
the imperfect

The form of the verb that is used to show an action in the past that has not been completed. In the sentence 'We were crossing the road', 'were crossing' is in the imperfect.

(Definition of “imperfect noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)