In my dialect of English, shared living arrangements (normally non-familial) can be described by three terms.
A housemate (or flatmate) is someone who shares your house (normally not your room, but this is open)
A roommate is someone who shares your room (normally not your bed, but see above)
A bedmate is self-explanatory.
In US English, “roommate” seems to cover all three, but US English speakers seem able to infer which is intended from the context. Can anyone help me with a usage guide?