Flatmates is used in the UK for someone who you share a flat with but have separate rooms, and roommates is used where you share a room, but not a bed, or are not in a romantic relationship with. It's generally for places like student accommodation.

[–] where_am_i@sh.itjust.works 4 points 2 weeks ago (1 children)

Yeah, but is it valid in American English to call someone a roommate even though each of you have a separate room?

[–] HonoraryMancunian@lemmy.world 6 points 2 weeks ago (1 children)

American English yes, British English no.

I'm unsure about other English-speaking countries.

[–] warbond@lemmy.world 1 points 2 weeks ago

My roommates got me a sweet car bed