The Collaborative International Dictionary of English v.0.48:

Cabbage \Cab"bage\ (k[a^]b"b[asl]j), n. [OE. cabage, fr. F.
   cabus headed (of cabbages), chou cabus headed cabbage,
   cabbage head; cf. It. capuccio a little head, cappuccio cowl,
   hood, cabbage, fr. capo head, L. caput, or fr. It. cappa
   cape. See Chief, Cape.] (Bot.)
   1. An esculent vegetable of many varieties, derived from the
      wild Brassica oleracea of Europe. The common cabbage has
      a compact head of leaves. The cauliflower, Brussels
      sprouts, etc., are sometimes classed as cabbages.
      [1913 Webster]

   2. The terminal bud of certain palm trees, used, like,
      cabbage, for food. See Cabbage tree, below.
      [1913 Webster]

   3. The cabbage palmetto. See below.
      [1913 Webster]

   Cabbage aphis (Zool.), a green plant-louse (Aphis
      brassic[ae]) which lives upon the leaves of the cabbage.


   Cabbage beetle (Zool.), a small, striped flea-beetle
      (Phyllotreta vittata) which lives, in the larval state,
      on the roots, and when adult, on the leaves, of cabbage
      and other cruciferous plants.

   Cabbage fly (Zool.), a small two-winged fly (Anthomyia
      brassic[ae]), which feeds, in the larval or maggot state,
      on the roots of the cabbage, often doing much damage to
      the crop.

   Cabbage head, the compact head formed by the leaves of a
      cabbage; -- contemptuously or humorously, and
      colloquially, a very stupid and silly person; a numskull.


   Cabbage palmetto, a species of palm tree (Sabal Palmetto)
      found along the coast from North Carolina to Florida.

   Cabbage rose (Bot.), a species of rose (Rosa centifolia)
      having large and heavy blossoms.

   Cabbage tree, Cabbage palm, a name given to palms having
      a terminal bud called a cabbage, as the Sabal Palmetto
      of the United States, and the Euterpe oleracea and
      Oreodoxa oleracea of the West Indies.

   Sea cabbage.(Bot.)
      (a) Sea kale
      (b) . The original Plant (Brassica oleracea), from which
          the cabbage, cauliflower, broccoli, etc., have been
          derived by cultivation.

   Thousand-headed cabbage. See Brussels sprouts.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cabbage tree
    n 1: Australian palm with leaf buds that are edible when young
         [syn: cabbage palm, cabbage tree, Livistona
         australis]
    2: tree with shaggy unpleasant-smelling toxic bark and yielding
       strong durable wood; bark and seeds used as a purgative and
       vermifuge and narcotic [syn: cabbage bark, cabbage-bark
       tree, cabbage tree, Andira inermis]
    3: elegant tree having either a single trunk or a branching
       trunk each with terminal clusters of long narrow leaves and
       large panicles of fragrant white, yellow or red flowers; New
       Zealand [syn: cabbage tree, grass tree, Cordyline
       australis]