Unlikely means probably not going to happen. An unlikely outcome, highly unlikely, it is unlikely that anybody noticed.
The pattern is unlikely to do something, or it is unlikely that. It also describes something surprising in combination: an unlikely friendship, an unlikely hero — where the point is that it did happen and nobody expected it. Note highly unlikely, which is one of the standard formulas of official denial; and that unlikely says something about probability rather than about whether anybody wants it.
1adjectiveunlikelyProbably not going to happen.
“It is unlikely that anybody will notice for about a year.”
synonyms: improbable, doubtful
2adjectivesurprisingSurprising in combination.
“It was an unlikely friendship and it lasted fifty years.”
unlikely is a degree of probability.
Likely comes from Old Norse likligr, meaning having the appearance of — from lik, a form or body, the same root as like. Something unlikely does not look as if it will happen, which is a judgement about appearances rather than odds.
Middle English
unlykely
English, today
unlikely
From Middle English unlykely. From Middle English unlykely,unlikly,unlykly,unlicli. by surface analysis, un- + likely.
Etymology from Wiktionary, CC BY-SA
Practised in Everyday Adjectives