1. to associate or socialize in a friendly way with someone
Usage: past tense of fraternize
2. to associate inappropriately with someone of lower rank or the enemy
Usage: military or professional context; often implies violation of rules

Examples

• The soldiers were punished for having fraternized with enemy troops.
• She fraternized with her coworkers at the company picnic.
• The officer was reprimanded for having fraternized with enlisted personnel.
• He fraternized with the locals during his travels abroad.
• The teacher was warned not to have fraternized with students outside of class.
• They fraternized with members of the opposing team after the game.