Deleterious, a.
Etymology: [LL. deleterius noxious, Gr. 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.
Shades of meaning
Fernald has no entry of its own for deleterious; he lists it under pernicious.
He lists it without comment; the entries above explain its neighbors.