An Etymological Dictionary of Astronomy and Astrophysics

Logic: Of an argument, if the premises are true, then the
conclusion cannot be denied without contradiction. The truth of the premises logically guarantees the truth of the conclusion.

Etymology (EN): M.E., from M.Fr. valide, from L. validus “strong, effective,” from valere “to be strong.”

Etymology (PE): Pâymand, from pâ, pây “foot; base, foundation, firmness” (Mid.Pers. pâd, pây; Av. pad- “foot;” cf. Skt. pat; Gk. pos, genitive podos; L. pes, genitive pedis; P.Gmc. *fot; E. foot; Ger. Fuss; Fr. pied; PIE *pod-/*ped-) + -mand possession suffix.