(archaic) second-person singular simple past form of can

(nonstandard) Contraction of couldn't've.

(Scotland) Contraction of could not.

simple past tense of can't seem

(UK, Ireland, Australia, New Zealand, vulgar, slang, idiomatic) Is unable even to organise a project that requires no planning; is incompetent.

(idiomatic, of a person) not musically talented, unable to sing.

Alternative form of could have, would have, should have

Used to wholeheartedly agree with somebody else's remark

Obsolete form of couldst.

Synonym of couldn't organise a piss-up in a brewery