Acrimonious

Bitter, hostile, or sharp in tone, especially during a dispute.

From acrimony +‎ -ous; compare French acrimonieux (“acrimonious”), from Latin ācrimōniōsus (“acrimonious”), from ācrimōnia (“pungency, sharpness; acrimony, austerity”) + -ōsus (suffix meaning “full of; prone to”, forming adjectives from nouns) (ultimately from Proto-Indo-European *-went- or *-wont- + *-to-). Ācrimōnia is derived from Latin ācer (“sharp; bitter, sour”) (from Proto-Indo-European *h₂eḱrós (“sharp”), from *h₂eḱ- (“sharp”) + *-rós (suffix forming adjectives from Caland system roots)) + Latin -mōnia (the feminine form of -mōnium (suffix forming collective nouns and nouns designating

acerb, acerbic, acrid, bitter, rancorous