n.
Pronunciation: in- ' ke-f ə -l ə n, -( ˌ )lin, en-
Function: noun
Etymology: enkephal- (alter. of encephal- ) + -in
Date: 1975
: either of two pentapeptides with opiate and analgesic activity that occur naturally especially in the brain and have a marked affinity for opiate receptors ― compare ENDORPHIN