mordacious
adjective
mor·da·cious
(ˈ)mȯ(r)¦dāshəs
1
: biting or given to biting
bitten in as with mordacious acid 
Times Literary Supplement
Times Literary Supplement2
: biting or sharp in manner or style : caustic
the lady's mordacious look showed plainly that she hated us all Pauline R. Fadiman
Pauline R. Fadiman mordaciously adverb
Word History
Etymology
Latin mordac-, mordax biting, given to biting (from mordēre to bite) + English -ious