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operant conditioning

n.
Psychology

A learning process in which the likelihood of a specific behavior increases or decreases in response to reinforcement or punishment that occurs when the behavior is exhibited, so that the subject comes to associate the behavior with the pleasure from the reinforcement or the displeasure from the punishment.

Indo-European & Semitic Roots Appendices

Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

Indo-European Roots

Semitic Roots

The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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