lunch room
In a private house, a room which may be used for luncheon as distinguished from dinner. It may be one with the breakfast room, and in that case may take either title. The reason for separating it from the dining room is generally in its smaller size and in the less elaborate character of the meals served there. 2. A room or group of rooms in which a simple restaurant service is carried on; especially in the business quarters of great cities where usually only the midday meal is required by persons who are far away from their homes. (Sturgis, 1900)