antagonistic (adj.)
- acrid
- adversative
- adverse
- aggressive
- alien
- anti
- antipathetic
- antithetic
- antonymous
- averse
- balancing
- bellicose
- belligerent
- bitter
- bloodthirsty
- bloody
- bloody-minded
- breakaway
- caustic
- chauvinistic
- clashing
- combative
- competitive
- conflicting
- contentious
- contradictory
- contrarious
- contrary
- converse
- counter
- counteractive
- counterpoised
- cranky
- cross
- crotchety
- despiteful
- detrimental
- difficult
- disagreeable
- discordant
- discrepant
- disharmonious
- disinclined
- disproportionate
- dissentient
- dissident
- dissonant
- divergent
- ferocious
- fierce
- fighting
- fractious
- grating
- hard
- harmful
- hateful
- hawkish
- hostile
- immiscible
- incompatible
- inconsistent
- indisposed
- inharmonious
- inimical
- inverse
- jangling
- jarring
- jingoistic
- malevolent
- malicious
- malignant
- martial
- militant
- militaristic
- military
- miserable
- negative
- nonconformist
- obstinate
- offensive
- opponent
- opposed
- opposing
- opposite
- oppositive
- perverse
- pugnacious
- quarrelsome
- rancorous
- reactionary
- reactive
- recalcitrant
- refractory
- repugnant
- resistant
- reverse
- revolutionary
- rigorous
- sanguinary
- sanguineous
- savage
- scrappy
- sinister
- soldierlike
- soldierly
- sore
- spiteful
- stressful
- trigger-happy
- troublesome
- troublous
- truculent
- trying
- uncongenial
- uncooperative
- unfavorable
- unfriendly
- unharmonious
- unpeaceable
- unpeaceful
- unpropitious
- untoward
- unwilling
- variant
- venomous
- virulent
- vitriolic
- warlike
- warring
- wretched
