roommate

Short definition from Wiktionary

Noun

1. 1
   A person with whom one shares a room, as in a dormitory, barracks, rooming house, or apartment.
2. 2
   A person sharing the same home albeit not the same room (but generally not a family member or spouse).
3. 3
   A same-sex significant other with whom one lives; a coinhabitant in a non-heterosexual relationship.