IPA: //ˈruːmˌmeɪt//
KK: /ˈrumˌmeɪt/
A person who lives with you and shares your living space, usually in a house or apartment.
My roommate and I often cook dinner together.
Roommate → It is formed from "room" (from Old English *rum*, meaning space or area) and "mate" (from Old English *gemetta*, meaning companion or associate). The word "roommate" refers to a companion or associate who shares a space or area with someone.
Think of a 'room' as a space you share and a 'mate' as a companion — that's why a roommate is someone who shares that space with you.