Roommate (noun)

A person with whom one shares a room, especially a dormitory room or apartment.

Origin:

Late 19th century: blend of room and mate.

Examples:

1. He is my college roommate.
2. She is my new roommate.
3. He's been my roommate for two years.
4. She's been looking for a new roommate.
5. He and his roommate have different schedules.