At least mordacious isn't as bad as that. Mordacious means biting, usually in a sarcastic sort of a way.
Sarcasm is said to be the lowest form of wit - which it is, unless you've ever spent time with four-year-olds, clowns, or accountants - but, hey, it's sometimes very funny and usually better than nothing.
And if it's intended to be hurtful, well, raising an eyebrow and saying isn't that somewhat mordacious? is a terrific way of pulling the rug from under the idiot's feet.
Word To Store Up To Use At Some Point: mordacious. This word isn't anything to do with the Latin mors, death, or the Latin morbus, illness, but the Latin mordax, from mordēre, to bite.