used for saying that if something does not happen, something else will happen or be true as a result
I can’t help you unless you tell me what’s wrong.
The car should be in the garage unless someone’s moved it.
Unless you come now, I’m going to leave without you.
Owen wouldn’t eat anything unless he’d cooked it himself.
not unless (=only if): ‘Are you going to stay overnight?’ ‘Not unless it’s absolutely necessary.’
Synonyms and related words