In linguistics, semelfactives are a type of aktionsart or lexical aspect, which is a property of verbs and other predicates representing the temporal flow of an event.
A semelfactive describes a very brief event which ends by returning to its initial state, making it capable of being repeated.
Semelfactive verbs in English include "blink", "sneeze", and "knock".
According to Bernard Comrie, who first posited the idea of semelfactive as a category of aktionsart, the event represented by a semelfactive verb is also perfective (treated as a complete action with no explicit internal temporal structure) and atelic (not having a goal).
Kearns considers semelfactives to be bounded but atelic, where telicity is understood as a kind of boundedness.