ETYM AS. biternys; biter better + -nys = -ness.
1. A sharp and bitter manner; SYN. acrimony, acerbity, jaundice.
2. The property of having a harsh unpleasant taste; SYN. bitter.

ETYM Cf. French exacerbation.
Violent and bitter exasperation.

ETYM Latin exasperatio: cf. French exaspération.
Actions that cause great irritation (or even anger).