"The reliable production of a response by a stimulus" (Catania, 1998, p. 8).
"A response component of a reflex; behavior that is elicited, or induced, by antecedent stimuli" (Cooper et al, 2007, p. 703).
"Behavior that is selected, maintained, and brought under stimulus control as a function of its consequences" (Cooper et al, 2007, p. 701).
"The reliable production of a response by a stimulus" (Catania, 1998, p. 8).
"A situation in which the frequency, latency, duration, or amplitude of a behavior is altered by the presence or absence of an antecedent stimulus" (Cooper et al, 2007, p. 705).
"An operant that occurs more frequently under some antecedent conditions than under others" (Cooper et al, 2007, p.694).
"A stimulus in the presence of which responses of some type have been reinforced and in the absence of which the same type of responses have occurred and not been reinforced" (Cooper et al, 2007, p. 694).