expression, i-adjective
cannot be ignored; cannot be taken lightly; requires serious attention
Used when something is too important or serious to be dismissed or handled carelessly. Often appears in formal or cautionary contexts.
この問題はゆるがせにできない。
This problem cannot be ignored.
安全対策はゆるがせにできない課題だ。
Safety measures are an issue that cannot be taken lightly.
Derived from the classical expression 忽せ (yurugase), meaning 'negligent' or 'careless', combined with the negative potential form of する, literally 'cannot be made light of'. The kanji 忽 is rare and not commonly used in modern Japanese.