informal a man or a boy
an equal in rank, power, or character; a peer
either of a pair; a mate
(usu in pl) a comrade or associate
(used before a noun) being a companion or associate; belonging to the same group
fellow travellers
Brit a member of an incorporated literary or scientific society
a person appointed to a salaried position allowing for advanced research
an incorporated member of a collegiate foundation
informal a boyfriend
[Old English feolaga partner, from Old Norse fēlagi, from fēlag partnership, from fē cattle, money + lag act of laying]