1That physically strengthens or reinforces itself.
2Of an action or process: that strengthens or reinforces itself; that causes itself to increase or intensify.
Reinforcing a behaviour by means of a self-administered reward or punishment; of or relating to self-reinforcement. More generally: reinforcing or strengthening one's own existing feelings, ideas, or habits.
Late 19th century. From self- + reinforcing, after self-reinforcement.