impractical; unpractical
Describes ideas, plans, or methods that are not realistic or workable in practice. Often used in formal or critical contexts.
The plan was criticized as impractical.
Just coming up with impractical ideas won't move things forward.
非現実的 means 'unrealistic' and emphasizes a disconnect from reality, while 非実際的 focuses on lack of practicality or feasibility.
実際的 is the antonym, meaning 'practical' or 'realistic'.
Formed from 非 (negative prefix) + 実際的 (practical). The derivation is transparent, but the exact historical origin is uncertain.