Unlikely (adjective)

1. Not probable or expected.
2. Not having a high probability of occurring or being the case.
3. Not having a good chance of success.

Origin:

Early 17th century (as an adverb in the sense "not like"): from un-1 + likely.

Examples:

1. It seems unlikely that he'll arrive on time.
2. It's unlikely that the team will win the championship this year.
3. It's unlikely that the experiment will produce the desired result.
4. The forecast says it's unlikely that it will rain tomorrow.
5. The outcome was unlikely, but it happened anyway.