The idiom "锱铢必较" is formed by combining "锱" and "铢", which are ancient Chinese units of weight representing very small amounts, to symbolize trivial or minor details; this is followed by "必", meaning "must", and "较", meaning "to dispute or calculate", thereby creating a compound phrase that literally denotes insisting on arguing over or meticulously calculating even the smallest matters, conveying the meaning of being extremely stingy or contentious over minor issues.