The Collaborative International Dictionary of English v.0.48:

Stillroom \Still"room`\, n.
   1. A room for distilling.
      [1913 Webster]

   2. An apartment in a house where liquors, preserves, and the
      like, are kept. [Eng.]
      [1913 Webster]

            Floors are rubbed bright, . . . stillroom and
            kitchen cleared for action.           --Dickens.
      [1913 Webster]

WordNet (r) 3.0 (2006):

stillroom
    n 1: a pantry or storeroom connected with the kitchen
         (especially in a large house) for preparing tea and
         beverages and for storing liquors and preserves and tea etc
         [syn: stillroom, still room]