The Collaborative International Dictionary of English v.0.48:
Mordacity \Mor*dac"i*ty\, n. [L. mordacitas: cf. F. mordacit['e]. See Mordacious.] The quality of being mordacious; biting severity, or sarcastic quality. --Bacon. [1913 Webster]WordNet (r) 3.0 (2006):
mordacity n 1: a disposition to biting