A fraternity (from Latin frater 'brother' and -ity; whence, "brotherhood") or fraternal organization is an organization, society, club or fraternal order traditionally of men but also women associated together for various religious or secular aims. Fraternity in the Western concept developed in the Christian context, notably with the religious orders in the Catholic Church during the Middle Ages. The concept was eventually further extended with medieval confraternities and guilds. In the early modern era, these were followed by fraternal orders such as Freemasons, the Rosicrucian Society of England, and Odd Fellows, along with gentlemen's clubs, student fraternities, and fraternal service organizations. Members are occasionally referred to as a brother or – usually in a religious context – frater or friar.
Today, connotations of fraternities vary according to context including companionships and brotherhoods dedicated to the religious, i.e., (Knights of Columbus), intellectual, academic, physical, or social pursuits of its members. In modern times, it sometimes connotes a secret society especially regarding Freemasonry, Odd Fellows, various academic, and student societies.