The word "validity" means the state of being factually or logically sound, with a solid basis on the truth. "Validity" can also indicate legal acceptability, authority or effectiveness, as in the case of the validity of a driver's license or a contract. Synonyms for "validity" include authority, certainty, cogency, effectiveness, foundation, grounds, legitimacy, potency, power, soundness, strength and validness.
The word "validity" is derived from the Late Latin word "validitas," which, in turn is related to the Medieval Latin "validus," meaning "strong," "robust" or "potent." The earliest known use of the word "validity" in the English language dates to the 16th century.