Frost  —n. 1 a frozen dew or vapour. B consistent temperature below freezing point. 2 cold dispiriting atmosphere. —v. 1 (usu. Foll. By over, up) become covered with frost. 2 a cover with or as with frost. B injure (a plant etc.) With frost. 3 make (glass) non-transparent by roughening its surface. [old english: related to *freeze]