flatmate Show phonetics
noun [C] UK
a person who shares an apartment with another person
roommate Show phonetics
1 a person with whom you share a room for a period of time:
Jean was my roommate during our first year at university.
2 US (UK housemate or flatmate) a person with whom you share an apartment or house:
Brian's moving out next month, so we're looking for another roommate to share our apartment.
(from Cambridge Advanced Learner's Dictionary)