Unworkable (adjective)

1. Incapable of being worked or put into practice.
2. Incapable of being used or function properly.
3. Incapable of being solved or resolved.

Origin:

Late 16th century (in the sense "incapable of being worked"): from un- (expressing negation) + workable.

Examples:

1. The proposed plan was deemed unworkable by the experts.
2. The machine was unworkable and had to be repaired.
3. The problem seemed unworkable, but he managed to find a solution.
4. The government's policies were deemed unworkable by the citizens.
5. The negotiation was declared unworkable and was adjourned.