roommate

A person with whom one shares a room or rooms.

One who shares a room with another or others.

One of two or more occupying the same room or rooms; one who shares the occupancy of a room or rooms; a chum.

A person with whom one shares a room, as at university etc.

A person with whom one shares an apartment or house (UK: flatmate or housemate).

an associate who shares a room with you