pheromone
n. a chemical signal that is released outside the body by members of a species and that influences the behavior of other members of the same species. For example, it may serve to attract a mate or to act as an alarm. In nonhuman animals, sensitivity to pheromones occurs via the vomeronasal system. The existence of true pheromones in humans is controversial, although scents (e.g., perfumes, body odors) may play a role in sexual attraction and arousal. Pheromones have also been suggested as a cause of menstrual synchrony. Also called ectohormone. Compare allomone.