n. a learning process in which an organism's behavior becomes dependent on the occurrence of a stimulus in its environment. See conditioned response. [ WordNet 1.5 ]
n. (Psychol.) A process for causing animals to behave in a specific manner by rewarding or punishing the animal each time it performs a certain act; after a time, the animal comes to associate the reward or punishment with the act, and will increase or decrease the frequency of performing that act. [ PJC ]