How to say "unrealistic" in Japanese

• むちゃくちゃJLPT N1approx.Common
  na-adjectiveFits when 'unrealistic' shades into unreasonable or absurd — a demand or expectation so far off it defies reason. A common word usually written in kana, it also covers the plain sense 'nonsensical'.
• 非現実的ひげんじつてき
  na-adjectiveThe direct equivalent for ideas, plans, or expectations that ignore reality; it also covers impractical and infeasible. Choose it when you simply mean that something cannot work in the real world.
  いつものごとく、彼かれの考かんがえはあまりに非ひ現実的げんじつてきだった。↗

  As usual, his thoughts were extremely academic.
• 世事に疎いせじにうとい
  expression, i-adjectiveDescribes a person rather than a plan: someone unrealistic because they know little of the world. For impractical ideas it is seldom the word you want; its real sense is inexperienced, naive about worldly affairs.

Use 「むちゃくちゃ」 when 'unrealistic' means absurd or unreasonable, 非現実的 for ideas or plans that ignore reality, and 「世事に疎い」 only for a person naive about the ways of the world.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• むちゃくちゃnonsensical
• 非現実的ひげんじつてきunrealistic
• 世事に疎いせじにうといinexperienced
• 夢見がちゆめみがち(tendency of being) unrealistic