noun ·Rare ·Advanced level

Definitions

Noun

1. 1
   A benzylisoquinoline alkaloid occurring in plants of the family Papaveraceae that has partial agonism for mu and delta opioid receptors, these effects are nalaxone reversible. uncountable, usually

Etymology

From proto- + opium + -ine.

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.