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):

bathroom
    n 1: a room (as in a residence) containing a bathtub or shower
         and usually a washbasin and toilet [syn: bathroom,
         bath]
    2: a room or building equipped with one or more toilets [syn:
       toilet, lavatory, lav, can, john, privy,
       bathroom]