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."