acrimonious

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 legal status or obligation), ultimately from Proto-Indo-European *-mō (suffix forming agent nouns from verbs)).