(1):

(v. t.) One who pertinaciously contends for some trifling things, as a point of etiquette; an unreasonable, obstinate contender; as, a stickler for ceremony.

(2):

(v. t.) One who stickles.

(3):

(v. t.) One who arbitrates a duel; a sidesman to a fencer; a second; an umpire.