Definition of: receptor

(ri·sep′tər) noun
1. Bacteriol. A combination of atoms in a cell that, by combining with extraneous substances, as drugs or toxins, may be thrown off from the cell and circulate in the blood, thus conferring immunity.
2. Physiol. The terminal structure, or free nerve ending, which is specialized to receive various forms of external and internal stimuli, transmitting them to the brain nerve centers: also called sense organ. Compare EFFECTOR. [<L, receiver]