イディオム

noun

idiom

A fixed expression whose meaning is not predictable from its parts; used in linguistics and everyday language.

• 「雨あめが降ふる」はイディオムではないが、「雨あめが降ふるように」はイディオムだ。

  'Ame ga furu' is not an idiom, but 'ame ga furu yō ni' is an idiom.