a. [ LL. deleterius noxious, Gr. dhlhth`rios, fr. dhlei^sqai to hurt, damage; prob. akin to L. delere to destroy. ] Hurtful; noxious; destructive; pernicious; as, a deleterious plant or quality; a deleterious example. -- Del`e*te"ri*ous*ly, adv. -- Del`e*te"ri*ous*ness, n. [ 1913 Webster ]