The story
Probably from m(ethyl) + irt- (“inversion of tri-”) + aza- (“nitrogen”) + -apine (“psychoactive tricyclic compound”).
Etymology from Wiktionary, CC BY-SA 4.0.
mirtazapine
Today it means: An antidepressant drug C₁₇H₁₉N₃ taken orally especially to treat major depressive disorder. It is marketed under the trademark Remeron. Full definition →