Unforeseeable (adjective)

Not foreseeable; unable to be predicted or anticipated.

Origin:

From un- + foreseeable.

Examples:

1. The unforeseeable events threw a wrench in the plan.
2. The unforeseeable outcome was a surprise.
3. The unforeseeable consequences were not taken into account.
4. Many unforeseeable factors can affect a situation.
5. The unforeseeable future is uncertain.