1. social organizations for male college students, typically having Greek letter names
2. groups of people sharing common interests or professions
3. the quality or state of being brotherly

Examples

• Many fraternities organize charity events on campus.
• He joined one of the oldest fraternities at his university.
• The fraternities competed in an annual sports tournament.
• Professional fraternities exist for doctors and lawyers.
• Some fraternities focus on academic achievement rather than social activities.
• The fraternities worked together to improve campus life.
• Military fraternities promote bonds among veterans.