Webster’s Revised Unabridged Dictionary · 1913 Viperoidea Vi′per·oi′de·a, Vi′per·oi′des, n. pl. [NL. See Viper, and -oid.] (Zoöl.) A division of serpents which includes the true vipers of the Old World and the rattlesnakes and moccasin snakes of America; — called also Viperina. ‹ Viperoid Viperous ›