prostaglandinPronunciation: /ˌprɒstəˈglandɪn/Definition of prostaglandin noun Biochemistry any of a group of compounds with varying hormone-like effects, notably the promotion of uterine contractions. They are cyclic fatty acids: the body’s production of prostaglandinsOrigin: 1930s: from prostate + gland1 + -in1prostaglandin in other Oxford dictionaries Definition of prostaglandin in the US English dictionary