1. to associate or socialize in a friendly way with someone
2. to associate with members of a hostile group, especially in a way that is considered disloyal
Usage: often disapproving

Examples

• The new employee fraternizes easily with her coworkers.
• He fraternizes with people from all walks of life.
• The coach warned players not to fraternize with opposing team members before the game.
• She was criticized for fraternizing with the enemy during wartime.
• The manager fraternizes with his staff at company social events.
• Military regulations prohibit officers from fraternizing with enlisted personnel.
• He fraternizes with his neighbors at weekend barbecues.