val·id / ˈvalid/ • adj. actually supporting the intended point or claim; acceptable as cogent: a valid criticism. ∎  legally binding due to having been executed in compliance with the law: a valid contract. ∎  legally acceptable: the visas are valid for thirty days.DERIVATIVES: va·lid·i·ty / vəˈlidətē/ n.val·id·ly adv.

VALID

Binding; possessing legal force or strength; legally sufficient.

A valid contract, for example, is one that has been executed in compliance with all the requisite legal formalities and is binding upon, and enforceable by, the individuals who executed it.

valid adequate in law XVI; well founded and applicable XVII. — F. valide or L. validus strong, powerful, effective, f. valēre be strong, etc.; see -ID1.
So validity XVI. — F. or late L.