The story
From German Prostaglandin. Equivalent to prosta(te) + gland + -in. So called because it was originally believed to be secreted by the prostate.
Etymology from Wiktionary, CC BY-SA 4.0.
prostaglandin
Today it means: Any of a group of naturally occurring lipids derived from the C₂₀ acid prostanoic acid; they have a number of physiological functions and may be considered to be hormones. Full definition →