invalidate

Invalidate is a verb meaning to render something invalid or void, or to undermine the validity or truth of something. It can mean legally or formally to declare something unenforceable or invalid, such as a contract, certificate, will, or election. It can also mean to discredit an argument, hypothesis, or claim by showing that its premises or evidence are insufficient or incorrect, thereby undermining its acceptability or credibility.

Etymology: Invalidate comes from in- (not) and valid (valid; legally acceptable). The term is used in English from the early modern period and retains both a formal/legal sense and a broader means of undermining credibility or usefulness.

Contexts

- Law and governance: to invalidate a law, ordinance, contract, test result, or vote by ruling or decision, or to render an agreement null and void.

- Logic and philosophy: to invalidate a theory or argument means to show a flaw in its logic or evidence, thereby undermining it.

- Computing: invalidation occurs with cache entries, sessions, or tokens to enforce state, security, and data integrity.

- Data and measurement: invalid data or invalidation of measurements occurs when data fail quality checks or are proven unreliable; data validation aims to prevent invalid data at entry.

In everyday usage, invalidate is closely tied to notions of nullification, reversal of legality, or rejection of a claim or result, and its scope ranges from formal structures to informal assessments.