Antagonism was a character trait that described someone who was confrontational, hostile, or opposing towards others.
According to T'Pol, Andorian-Vulcan relations weren't always as antagonistic as they had become by 2153. (ENT: "Proving Ground")
In 2370, Byleth, an Iyaaran visiting USS Enterprise-D, asked Worf what the antimatter replenishment rate was. When Worf confessed his ignorance, Byleth then turned to Geordi La Forge and asked him if he was smarter than the Klingon. When Geordi asked him why he wanted to know, he changed the subject. This was part of the Iyaaran's plan to understand antagonism by provoking Worf to anger. (TNG: "Liaisons")
In 2376, according to The Doctor, Lewis Zimmerman's anxiety was manifesting as agoraphobia, paranoia and antagonism. (VOY: "Life Line")