To be antisocial was to refuse to socialize with others, or to interact with others in an abnormal or harmful way.
In 2268, Doctor Leonard McCoy suggested that as a father might protect their child despite that child's becoming antisocial and even committing murder, so Richard Daystrom might be protecting the M-5 multitronic unit he'd created. (TOS: "The Ultimate Computer")
In 2370, Data postulated that if interphasic organisms were affecting him unconsciously, they might have caused his waking dreams and the antisocial behavior that followed. (TNG: "Phantasms")