n.1. The act or process of reinforcing or the state of being reinforced.
2. Something that reinforces.
3. often reinforcements Additional personnel or equipment sent to support a military action.
4. Psychology a. The occurrence or experimental introduction of an unconditioned stimulus along with a conditioned stimulus.
b. The strengthening of a conditioned response by such means.
c. An event, circumstance, or condition that increases the likelihood that a given response will recur in a situation like that in which the reinforcing condition originally occurred.