1. The quality of being mordacious; sharp or sarcastic in style or tone.
2. A readiness or tendency to bite things.
The author's droll mordacity helps capture the sense of discontent and disillusionment that was prevalent in Northern England in the closing years of Thatcher's premiership
Michael's irrepressible mordacity ensured that his possessions, what few he had, as well as any individuals who came across him, very quickly found themselves covered in vicious bite marks
sharp or caustic in style, and in tone. Sarcastic. mean. To be in an assholemood.
A wife would say this to her husband who comes home in a harsh, bad mood everyday because he hates his job:
"Listen, don't come home being a mordacious prick everyday because you can't handle your job".