Imperfectivum

Imperfectivum, or the imperfective aspect, is a grammatical category that marks actions as not viewed as complete. It characterizes events as ongoing, habitual, repeated, or without reference to their termination, and is typically contrasted with the perfective aspect, which presents a complete, bounded event.

Across languages, imperfective is encoded in verb morphology, periphrastic constructions, or both. In Slavic languages such as Russian and Polish, imperfective forms are distinguished from their perfective counterparts by aspectual morphology or by using different verb stems; for example, Russian pisat’ (to write) is imperfective, while napisat’ is perfective, and Polish pisac versus napisac. English marks imperfective through aspect like the present or past progressive (I am writing, I was writing), or through habitual phrases (I write every day).

Imperfective use covers various temporal meanings: ongoing actions in the moment of speech, customary or habitual actions, and situations described without focusing on completion. It also serves as background framing in narrative and can interact with tense to indicate relative timing.

The term imperfectivum is used in linguistic tradition to denote imperfective forms. In some languages the category is productive and morphologically marked; in others it is expressed by periphrastic means or not distinguished at all. The interaction of imperfective with tense and mood contributes to the granularity of an language’s aspectual system.