idiom from Chinese history or classics
Refers to set phrases or proverbs originating from historical events or classical Chinese literature, often used in Japanese as four-character compounds.
"Mujun" (contradiction) is a famous idiom from Chinese history.
He often uses classical Chinese idioms in his speeches.
四字熟語 is a broader category of four-character compounds, while 故事成語 specifically refers to those derived from Chinese historical events or classical texts.
ことわざ are proverbs in general, often of Japanese origin, whereas 故事成語 are idioms with a Chinese historical or literary background.
From 故事 (historical event or classical story) + 成語 (set phrase). The term itself is a Japanese coinage referring to Chinese-derived idioms.