n.
Pronunciation: en- ' do ̇ r-f ə n
Function: noun
Etymology: International Scientific Vocabulary end ogenous + m orphin e
Date: 1976
: any of a group of endogenous peptides (as enkephalin) found especially in the brain that bind chiefly to opiate receptors and produce some pharmacological effects (as pain relief) like those of opiates specifically : BETA-ENDORPHIN