A storeroom is a room used for keeping supplies, equipment, or goods that aren't needed right at the moment but will be used later. Schools have storerooms where they keep extra textbooks, art supplies, and cleaning materials. Restaurants store ingredients, extra plates, and backup equipment in their storerooms. Museums keep artifacts they're not currently displaying in climate-controlled storerooms.

The word tells you both what the room is for (storing things) and what it is (a room). A storeroom is different from a closet, which is usually smaller and built into a wall, or a warehouse, which is a huge building for storing large quantities of goods. A storeroom is typically a dedicated room within a larger building.

You might also see the word written as two words: store room. Both spellings mean the same thing. When a teacher says “I need to grab something from the storeroom,” they mean that dedicated space where the school keeps its reserves and backup supplies organized and out of the way until they're needed.