The Collaborative International Dictionary of English v.0.48:

Storeroom \Store"room`\, n.
   Room in a storehouse or repository; a room in which articles
   are stored.
   [1913 Webster]

WordNet (r) 3.0 (2006):

storeroom
    n 1: a room in which things are stored [syn: storeroom,
         storage room, stowage]

Moby Thesaurus II by Grady Ward, 1.0:

68 Moby Thesaurus words for "storeroom":
   archives, armory, arsenal, attic, attic room, bank, basement, bay,
   bin, bonded warehouse, bookcase, box, bunker, buttery, cargo dock,
   cellar, chest, closet, cockloft, conservatory, crate, crib,
   cupboard, depository, depot, dock, drawer, dump, exchequer, garret,
   glory hole, godown, hayloft, hold, hutch, junk room, kitchen,
   library, locker, loft, lumber room, lumberyard, magasin, magazine,
   rack, repertory, repository, reservoir, rick, shelf, sky parlor,
   smoking room, stack, stack room, stock room, storage, store,
   storehouse, supply base, supply depot, tank, treasure house,
   treasure room, treasury, vat, vault, warehouse, wine cellar