Real Dictionary

fraternity
countable noun: In the United States, a fraternity is a society of male university or college students.
countable noun: You can refer to people who have the same profession or the same interests as a particular fraternity.
uncountable noun: Fraternity refers to friendship and support between people who feel they are closely linked to each other.

fraternity in American English
the state or quality of being brothers; fraternal relationship or spirit; brotherliness
noun: a local or national organization of male students, primarily for social purposes, usually with secret initiation and rites and a name composed of two or three Greek letters

fraternity in British English
noun: a body of people united in interests, aims, etc