The Collaborative International Dictionary
Mordacious \Mor*da"cious\, a. [L. mordax, -acis, fr. mordere, morsum, to bite. See Morsel.] Biting; given to biting; hence, figuratively, sarcastic; severe; scathing. -- Mor*da"cious*ly, adv.
Douglas Harper's Etymology Dictionary
"given to biting," 1640s (originally figurative), from Latin mordac-, stem of mordax, from mordere "to bite," perhaps from PIE root mer- (2) "to rub, harm" (see smart (v.)). Related: Mordacity.
Wiktionary
a. 1 Biting, causing a physical bite or sting; corrosive 2 sharp or caustic in style or tone. 3 Prone to biting, aggressive (of an animal etc.). 4 Sharp in intent, sarcastic
WordNet
Usage examples of "mordacious".
His mordacious propinquity casts a reviling sensation of obscenity about me.
Huld, hopeless and without honor, committed to his endless servitude, his mordacious kinship with horror, and I imagine that he follows them there, down those endless halls, watering the sterile dust with his tears.