'借故' is a verb meaning 'to make an excuse'—literally 'borrow a reason' (借 jiè = to borrow; 故 gù = reason, pretext, or cause). It implies using a seemingly legitimate or plausible justification to avoid doing something, often with an element of evasion or insincerity. The word carries a mildly negative connotation and is commonly used in formal or written Chinese, though it appears in spoken contexts too—especially when describing someone’s deliberate avoidance of responsibility, obligation, or an uncomfortable situation.

This compound is typically followed by a verb phrase indicating the avoided action (e.g., 借故离开, 借故推脱). Unlike casual expressions like 找借口, 借故 sounds more refined and slightly critical, suggesting premeditated or socially polished evasion rather than blunt dishonesty. It frequently appears in news reports, workplace discussions, or interpersonal narratives where motives are being analyzed or questioned.