- a restaurant where light, quick meals, as lunches, are served
- a room in an office, school, etc. where lunches, usually brought in, may be eaten
- A luncheonette.
- A room in a facility, such as a school, in which lunches may be purchased or those brought from home may be eaten.
- A room reserved for eating food, especially at a business (lunch may or may not be served there).
- We made a point to eat in the lunchroom, not at our desks.
- A diner or restaurant that specializes in serving lunch.
- I don't know how they stay in business serving only lunch, but the lunchroom on the corner is cheap and fast so I like it.