isn't
v.v. the short way to say or write 'is not'. You use it to say that something is not true or to describe what someone is not doing.
v. the contracted form of 'is not', used to negate a third-person singular subject. Functions as an auxiliary verb or a copula in negative constructions.
He isn't coming to the party tonight.
The weather forecast says it will rain, but it isn't raining at the moment.
While the proposal sounds promising on paper, it isn't necessarily the most cost-effective solution for a small business with limited capital.
From is + -n't.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
A contraction of 'is' and 'not'. In formal writing, the full form 'is not' is generally preferred over the contraction.
They isn't here.They aren't here.Learners sometimes use 'isn't' for all subjects, but it only agrees with third-person singular subjects like 'he', 'she', or 'it'.
Last updated May 2, 2026