UNLIKELY
unlikely
(adjective) has little chance of being the case or coming about; “an unlikely story”; “an unlikely candidate for reelection”; “a butcher is unlikely to preach vegetarianism”
improbable, unlikely
(adjective) not likely to be true or to occur or to have occurred; “legislation on the question is highly unlikely”; “an improbable event”
improbable, unbelievable, unconvincing, unlikely
(adjective) having a probability too low to inspire belief
Source: WordNet® 3.1
Etymology
Adjective
unlikely (comparative unlikelier or more unlikely, superlative unlikeliest or most unlikely)
Not likely; improbable; not to be reasonably expected.
Not holding out a prospect of success; likely to fail; unpromising.
Adverb
unlikely (comparative more unlikely, superlative most unlikely)
In an improbable manner.
Noun
unlikely (plural unlikelies)
Something or somebody considered unlikely.
Source: Wiktionary
Un*like"ly, a.
1. Not likely; improbable; not to be reasonably expected; as, an
unlikely event; the thing you mention is very unlikely.
2. Not holding out a prospect of success; likely to fail;
unpromising; as, unlikely means. Hooker.
3. Not such as to inspire liking; unattractive; disagreeable. [Obs.]
"The unlikely eld of me." Chaucer.
Un*like"ly, adv.
Definition: In an unlikely manner.
Source: Webster’s Unabridged Dictionary 1913 Edition