butyrChem. An adaptation of L. butyrum butter, sometimes used in technical senses. 1840H. Cleeve in Jrnl.Agric.Soc. I. iii. 321 Butyr, (or, as it is commonly called, butter) of antimony.1882Chemist & Drug. XXIV. 56/1 Butyr of antimony, oil of vitriol, etc.