Synonyms for unlikely

modified

1. Not likely to happen

   improbable, unheard-of, incredible, implausible, not to be thought of, unbelievable, absurd, palpably false, unconvincing, not likely, scarcely possible, apparently false, contrary to expectation, inconceivable, doubtful, dubious, questionable, untoward, extraordinary, marvelous, out of the ordinary, strange.

2. Not likely to succeed

   unpromising, unpropitious, questionable, dubious.

   Antonyms likely*, probable, credible.