fellow

One of a pair.

“one eye was blue but its fellow was brown”

A man who is the lover of a man or woman.

A person who is member of one's class or profession.

“he sent e-mail to his fellow hackers”

A friend who is frequently in the company of another.

An informal form of address for a man.

“Say, fellow, what are you doing?”

A boy or man.

“there's a fellow at the door”

A member of a learned society.

“he was elected a fellow of the American Physiological Association”