1. [ adjective ] not likely to be true or to occur or to have occurred
Synonyms: unlikely

"legislation on the question is highly unlikely" "an improbable event"

Related terms: probable supposed
2. [ adjective ] having a probability to low to inspire belief
Synonyms: unconvincing unlikely unbelievable
Related terms: implausible
3. [ adjective ] too improbable to admit of belief
Synonyms: marvelous tall marvellous

"a tall story"

Related terms: incredible
Similar spelling:   improvable