The Collaborative International Dictionary of English v.0.48:

Gumbo \Gum"bo\ (g[u^]m"b[-o]), n. [Written also gombo.]
   1. A soup thickened with the mucilaginous pods of the okra;
      okra soup. Especially, A thick stew made with chicken
      (chicken gumbo), or seafood (seafood gumbo), thickened
      with okra or file, and also containing greens and often
      hot spices; it is particularly popular in Louisiana.
      [1913 Webster]

   2. The okra plant or its pods.
      [1913 Webster]

WordNet (r) 3.0 (2006):

gumbo
    n 1: any of various fine-grained silty soils that become waxy
         and very sticky mud when saturated with water [syn:
         gumbo, gumbo soil]
    2: tall coarse annual of Old World tropics widely cultivated in
       southern United States and West Indies for its long
       mucilaginous green pods used as basis for soups and stews;
       sometimes placed in genus Hibiscus [syn: okra, gumbo,
       okra plant, lady's-finger, Abelmoschus esculentus,
       Hibiscus esculentus]
    3: long mucilaginous green pods; may be simmered or sauteed but
       used especially in soups and stews [syn: gumbo, okra]
    4: a soup or stew thickened with okra pods