The Chinese idiom 无缘无故 is formed through a parallel and repetitive classical structure common in chengyu (成语), where 无 (wú, meaning "without") is repeated to negate two synonymous nouns. Here, 缘 (yuán) refers to "cause" or "reason" (as in relationships or origins), and 故 (gù) means "cause" or "purpose". The paired terms 缘 and 故 are near-synonyms, so the compound 无缘 (without cause) and 无故 (without reason) are combined in a four-character template to create strong rhetorical emphasis. The resulting phrase 无缘无故 literally means "without cause or reason", and its formation exemplifies a reinforcing binome pattern where repetition intensifies the meaning of having absolutely no justification or basis.