违宪 literally means 'to violate the constitution' — 违 (wéi) means 'to violate, contravene', and 宪 (xiàn) is short for 宪法 (xiànfǎ), meaning 'constitution'. Together, 违宪 functions as an adjective describing laws, regulations, government actions, or judicial decisions that conflict with constitutional principles or provisions. It is a formal, legal term used almost exclusively in official, academic, or media discourse about governance, rights protection, and rule-of-law mechanisms.

In China, the term carries strong institutional weight: courts or the National People’s Congress Standing Committee may review whether legislation is 违宪, and such findings can lead to annulment or revision. While not used in casual speech, it appears frequently in legal commentary, news reports on judicial reform, and constitutional education materials. Its tone is serious and authoritative, signaling fundamental legal inconsistency rather than mere policy disagreement.