What are the opposite words for invalid?

Invalid is commonly used to refer to someone or something that is not valid, not legally or medically recognized, or not accepted by a particular system or authority. Antonyms for the word 'invalid' could be valid, genuine, authentic, credible, reliable, sound, legal, lawful, legitimate, approved, certified, and official. These terms imply that something is recognized, accepted, and approved by the relevant authority or system, legally and factually compliant to pertinent regulations, standards, and norms, and not subject to doubt, suspicion, or rejection. Validity, credibility, and authenticity are essential attributes that enhance trust, confidence, and credibility in any field or context. Hence, knowing the antonyms of the word invalid is crucial in determining the worthiness, legitimacy, and authenticity of any transaction, statement, or claim.

Antonym of the day

let the cat ouf bag
be quiet, conceal, hide.