ranitidine UK /ɹaˈnɪt.ɪ.diːn/US /ɹəˈnɪt.ɪˌdin/ noun1 •A furan (trademark Zantac) which blocks the histamine H₂-receptors, to prevent the secretion of gastric acid.The huge sales of one drug in particular, ranitidine (sold under the trade name Zantac®), helped to lift the British pharmaceutical company Glaxo into the world league. — 2001