The Collaborative International Dictionary of English v.0.48:

Adobe \A*do"be\ ([.a]*d[=o]"b[asl]), n. [Sp.]
   1. An unburnt brick dried in the sun; also used as an
      adjective, as, an adobe house, in Texas or New Mexico.
      [1913 Webster]

   2. Earth from which unburnt bricks are made. [Western U. S.]
      [Webster 1913 Suppl.]

   3. (Geol.) Alluvial and playa clays of desert and arid
      regions, differing from ordinary clays of humid regions in
      containing carbonates and other soluble minerals.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

adobe
    n 1: the clay from which adobe bricks are made
    2: sun-dried brick; used in hot dry climates [syn: adobe,
       adobe brick]