phy·so·stig·mine (fī'sō-stĭg'mēn') n. A crystalline alkaloid, C15H21N3O2, extracted from the Calabar bean, used in medicine as a miotic and cholinergic agent and to enhance memory in patients with Alzheimer's disease. Also called eserine.
[New Latin Phȳsostigma, genus name of the Calabar bean (Greek phūsa, bellows + stigma) + -ine2.]