From WordNet (r) 2.0 (August 2003) [wn]:
storeroom
n : a room in which things are stored [syn: storage room,
stowage]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Storeroom \Store"room`\, n.
Room in a storehouse or repository; a room in which articles
are stored.
[1913 Webster]