n. & v.
n. 1 a something that completes. b one of a pair, or one of two things that go together. 2 (often full complement) the full number needed to man a ship, fill a conveyance, etc. 3 Gram. a word or phrase added to a verb to complete the predicate of a sentence. 4 Biochem. a group of proteins in the blood capable of lysing bacteria etc. 5 Math. any element not belonging to a specified set or class. 6 Geom. the amount by which an angle is less than 90ø (cf. SUPPLEMENT).
v.tr. 1 complete. 2 form a complement to (the scarf complements her dress). complemental adj.
[ ME f. L complementum (as COMPLETE) ]