friend has 8 distinct synonyms spread across 4 of its 5 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is foe.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a person you know well and regard with affection and trust
“he was my best friend at the university”
an associate who provides cooperation or assistance
“he's a good ally in fight”
a person with whom you are acquainted
“I have trouble remembering the names of all my acquaintances”
a person who backs a politician or a team etc.
“all their supporters came out for the game”
Synonyms, antonyms and the broader and narrower relations for friend come from Princeton University’s WordNet. Full sources and licences.