couldn't
KUUD-nt/ˈkʊd.n̩t/
- 1Contraction of "could not," used to express that something was impossible, not allowed, or beyond someone's ability.
He couldn't believe how much the city had changed.
The hikers couldn't reach the summit before nightfall.
Note
Beyond plain inability, the contraction does quiet social work. Put into a negative question with a tag, it softens a request into something easy to refuse: You couldn't lend me a lighter, could you? Standing alone after an offer, with the rest of the verb left unsaid, it declines graciously: No thanks, I couldn't. In both, the speaker frames the matter as what cannot be done rather than what is not wanted.
Use it in a sentence
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Origin
Formed from "could" combined with the contraction "n't", meaning "not".