QUESTION: What two words are combined to create the portmanteau word, “endorphin”?

Answer: endogenous and morphine.

Endogenous is defined as follows: “(1) Growing or produced by growth from deep tissue. (2) Caused by factors inside the organism or system. (3) Produced or synthesized within the organism or system.”

Morphine is “A bitter crystalline addictive narcotic base C17H19NO3 that is the principal alkaloid of opium and is used in the form of a soluble salt as an analgesic and sedative.”

An endorphin is a endogenous opioid neuropeptide. It is a “morphine-like substance originating within the body.” Endorphins are produced by the pituitary gland and the central nervous system.