The Collaborative International Dictionary of English v.0.48:

Lavatory \Lav"a*to*ry\, a.
   Washing, or cleansing by washing.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Lavatory \Lav"a*to*ry\, n.; pl. Lavatories. [L. lavatorium:
   cf. lavatoire. See Lave to wash, and cf. Laver.]
   1. A place for washing.
      [1913 Webster]

   2. A basin or other vessel for washing in.
      [1913 Webster]

   3. A wash or lotion for a diseased part.
      [1913 Webster]

   4. A place where gold is obtained by washing.
      [1913 Webster]

   5. A room containing one or more sinks for washing, as well
      as one or more toilet fixtures; also called bathroom,
      toilet, and sometimes commode. Commode and toilet may
      refer to a room with only a toilet fixture, but without a
      sink.

   Syn: toilet, lavatory, can, facility, john, privy, bathroom.
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

lavatory
    n 1: a room or building equipped with one or more toilets [syn:
         toilet, lavatory, lav, can, john, privy,
         bathroom]
    2: a bathroom sink that is permanently installed and connected
       to a water supply and drainpipe; where you can wash your
       hands and face; "he ran some water in the basin and splashed
       it on his face" [syn: washbasin, basin, washbowl,
       washstand, lavatory]
    3: a toilet that is cleaned of waste by the flow of water
       through it [syn: flush toilet, lavatory]