harsh or bitter language that conveys great criticism and ill-will;
e.g. She spewed vitriol on them about all of her pent-up frustrations.
(noun)
in old or literary usage, concentrated sulfuric acid, or a sulfate of a metal such as iron, copper, or zinc (especially the crystalline hydrated forms of these compounds);
e.g. He added vitriol to the mixture as part of the final stage of preparation.