Definition of "Friend" :

noun: a member of the Religious Society of Friends founded by George Fox (the Friends have never called themselves Quakers)

noun: a person with whom you are acquainted

"We are friends of the family."

noun: an associate who provides cooperation or assistance

noun: a person you know well and regard with affection and trust

"He was my best friend at the university."

noun: a person who backs a politician or a team etc.

"They are friends of the library."