IPA: /ˈæntəˌruːm/
KK: /ˈæntəˌrum/
A room that is located before another room, usually serving as a waiting area or entrance.
She sat in the anteroom, waiting for her appointment to begin.
Anteroom → It is formed from "ante-" (meaning before) and "room" (from Old French *rom*, meaning a space or area). The word "anteroom" refers to a room that is situated before another room, typically serving as a waiting area.
Think of a space that is 'before' another room — 'ante-' means before, and 'room' refers to a space. An anteroom is a room that comes before another.