Apply  v. (-ies, -ied) 1 (often foll. By for, to, or to + infin.) Formally request. 2 be relevant. 3 a make use of; employ (apply the rules; apply common sense). B operate (apply the brakes). 4 (often foll. By to) put or spread on. 5 refl. (often foll. By to) devote oneself. [latin applico fasten to]