Synonyms of unlikely in English:

unlikely


See US English definition of unlikely

See UK English definition of unlikely

See Spanish definition of improbable

adjective

1‘it is unlikely that the band will play here again this year’

SYNONYMS
improbable, not likely, doubtful, dubious, unexpected, beyond belief, implausible
ANTONYMS

likely, certain

2‘they laughed at themselves for believing such an unlikely story’

SYNONYMS
implausible, improbable, questionable, unconvincing, remote, far-fetched, strained, laboured, unrealistic, incredible, unbelievable, inconceivable, unimaginable, fantastic, fabulous, fanciful, ridiculous, absurd, preposterous
informal tall, cock and bull, hard to swallow, hard to take
ANTONYMS

likely, believable