fel·low 
(fĕlō)
(fĕlō)n.
1.
a. A man or boy.
b. Informal A boyfriend.
2. A comrade or associate.
3.
a. A person of equal rank, position, or background; a peer.
b. One of a pair; a mate: found the lost shoe and its fellow.
4. A member of a learned society or professional organization.
5.
a. A graduate student appointed to a position granting financial aid and providing for further study.
b. A physician who enters a training program in a medical specialty after completing residency, usually in a hospital or academic setting.
6. Chiefly British
a. An incorporated senior member of certain colleges and universities.
b. A member of the governing body of certain colleges and universities.
7. Archaic A man or boy held in low regard.
adj.
Being of the same kind, group, occupation, society, or locality; having in common certain characteristics or interests: fellow workers.
[Middle English felau, from Old English fēolaga, from Old Norse fēlagi, business partner, fellow, from fēlag, partnership : fē, property, money; see peku- in the Appendix of Indo-European roots + lag, a laying down; see legh- in the Appendix of Indo-European roots.]