ci·met·i·dine 
(sĭ-mĕtĭ-dēn′, -dīn′)
(sĭ-mĕtĭ-dēn′, -dīn′)n.
A histamine receptor antagonist, C10H16N6S, that inhibits acid secretion in the stomach and is used to treat duodenal and gastric ulcers and gastroesophageal reflux disease.
[Alteration of CY(ANO-) + MET(HYL) + (GUAN)IDINE.]