The best replacement for roommate is room mate.

The best alternatives to roommate are rated as following:
★★★★★  room mate
★★★★★  tenant
★★★  no roommate
★★★  live alone
★★  living alone
★★  alone
★★  housemate
★★  roomate
★★  spouse
★  single white female
★  roommate
★  husband
★  single dorm
★  boyfriend
★  suitemate
★  border
★  studio
  dog roommate
  sublet
  wife
  not to roommate
  flatmate

Your alternative for roommate is not listed? Suggest!
Speaking about roommate, one probably shouldn't forget about married couple.

Other search terms related to roommate and their ratings are:
★★★★★ married couple
You have in mind a companion for roommate and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of roommate in all years. Click on graph for more.
roommate
room mate
tenant