valid Definition

valid
adj

1a. Said of an argument, objection, etc: based on truth or sound reasoning;

Thesaurus: sound, logical, accurate, cogent, right, convincing, compelling, genuine, authentic, legitimate; Antonym: fallacious.
1b. Said of an argument, objection, etc: well-grounded; having some force.
2a. Said of a ticket or official document: legally acceptable for use;

Example: a valid passport
2b. Said of a ticket or official document: not having reached its expiry date.

Example: The ticket is still valid
3. Said of a contract: drawn up according to proper legal procedure.

Derivative: validity
noun

The truth, soundness or force of a statement
Thesaurus: strength, weight, substance, efficacy, soundness, accuracy, correctness, truth, authority, legitimacy.

Derivative: validly
adverb

Etymology: 16c: from Latin validus strong, from valere to be strong.