a member of the Religious Society of Friends founded by George Fox (the Friends have never called themselves Quakers)
a person who backs a politician or a team etc.
"all their supporters came out for the game"
"they are friends of the library"
a person with whom you are acquainted
"I have trouble remembering the names of all my acquaintances"
"we are friends of the family"
an associate who provides cooperation or assistance
"he's a good ally in fight"
a person you know well and regard with affection and trust
"he was my best friend at the university"