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".
From [mondo (bizarro), very bizarre, from Italian Mondo)
Acious-
a suffix forming adjectives that correspond to nouns ending in the suffixes -acity and -acy: audacious; fallacious.ZI
That is one mondacious vehicle. Your girl is very mondacious.