From WordNet (r) 3.0 (2006) [wn]:
storeroom
n 1: a room in which things are stored [syn: storeroom,
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]