What is the meaning of fellow?

noun

• A boy or man.
  • usage: "that chap is your host"; "there's a fellow at the door"; "he's a likable cuss"; "he's a good bloke"
  • synonyms: chap, feller, fella, lad, gent, blighter, cuss, bloke
• A friend who is frequently in the company of another.
  • usage: "drinking companions"; "comrades in arms"
  • synonyms: companion, comrade, familiar, associate
• A person who is member of one's class or profession.
  • usage: "the surgeon consulted his colleagues"; "he sent e-mail to his fellow hackers"
  • synonyms: colleague, confrere
• One of a pair.
  • usage: "he lost the mate to his shoe"; "one eye was blue but its fellow was brown"
  • synonyms: mate
• A member of a learned society.
  • usage: "he was elected a fellow of the American Physiological Association"
• An informal form of address for a man.
  • usage: "Say, fellow, what are you doing"; "Hey buster, what's up"
  • synonyms: dude, buster
• A man who is the lover of a girl or young woman.
  • usage: "if I'd known he was her boyfriend I wouldn't have asked"
  • synonyms: boyfriend, beau, swain, young man