[vit.ri.ol] n [ME, fr. MF, fr. ML vitriolum, alter. of LL vitreolum, neut. of vitreolus glassy, fr. L vitreus vitreous] (14c) 1 a: a sulfate of any of various metals (as copper, iron, or zinc); esp: a glassy hydrate of such a sulfate b: oil of vitriol
2: something felt to resemble vitriol esp. in caustic quality; esp: virulence of feeling or of speech -- vit.ri.ol.ic adj