pheromone /fer″əmōn′/ [Gk, pherein, to carry, hormaein, to stimulate] , a substance secreted by an organism that elicits a particular response from another individual of the same species, usually of the opposite sex. Pheromones may be sexual stimulants or attractants or alarm or trail-making substances; in social insects they have a role in the determination of castes.
