fellow
noun
a boy or man
“that chap is your host”
“there's a fellow at the door”
a friend who is frequently in the company of another
“drinking companions”
“comrades in arms”
a person who is member of one's class or profession
“the surgeon consulted his colleagues”
“he sent e-mail to his fellow hackers”
one of a pair
“he lost the mate to his shoe”
“one eye was blue but its fellow was brown”
Synonymsmatea member of a learned society
“he was elected a fellow of the American Physiological Association”
an informal form of address for a man
“Say, fellow, what are you doing?”
“Hey buster, what's up?”
a man who is the lover of a man or woman
“if I'd known he was her boyfriend I wouldn't have asked”
“When the law changed, Pet could finally married his long-time boyfriend Jim”
Source: WordNet 3.1, Princeton University