(1) A readiness to perceive or respond in some way; an attitude that facilitates or predetermines an outcome, e.g., prejudice or bigotry as a set to respond negatively, independently of the merits of the stimulus. (2) To reduce a fracture, i.e., to bring the bones back into a normal position or alignment. (3) Defined group of events, objects, data, distinguishable from other groups. [M.E. sette, fr. O.Fr., fr. Med. L. secta, course, fr. sequor, to follow]