Definition of "antagonistic"

They were distinct, adverse, even antagonistic.

1855, Henry Hart Milman, History of Latin Christianity‎

Though the tephrosia is a powerful agent, and, if carried too far beyond the antagonistic action of the poison, is, I presume, not entirely without danger, I have never known any bad symptoms to arise from its use.

1866, American Journal of Pharmacy and the Sciences Supporting Public Health

And deputies from opposing parties, inherently more antagonistic than deputies from the same party, can be bought at a lower price.

2002, Barry Ames, The Deadlock of Democracy in Brazil, page 171

The tone of congressional hearings involving tech industry executives in recent years can best be described as antagonistic.

2023 May 16, Cecilia Kang, “OpenAI’s Sam Altman Urges A.I. Regulation in Senate Hearing”, in The New York Times‎