veneficial adjective1 •(no longer used, old-fashioned) Poisonous or poisoning; pertaining to poison; malignant, sorcerous.Why the Goddesses sit commonly crosse-legged in ancient draughts, Since Juno is described in the same as a veneficial posture to hinder the birth of Hercules? — 1658 formsmore veneficial · most veneficial