The Collaborative International Dictionary of English v.0.48:

Rib \Rib\, v. t. [imp. & p. p. Ribbed; p. pr. & vb. n.
   Ribbing.]
   1. To furnish with ribs; to form with rising lines and
      channels; as, to rib cloth.
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   2. To inclose, as with ribs, and protect; to shut in.
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            It [lead] were too gross
            To rib her cerecloth in the obscure grave. --Shak.
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   To rib land, to leave strips of undisturbed ground between
      the furrows in plowing.
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The Collaborative International Dictionary of English v.0.48:

Ribbed \Ribbed\, a.
   1. Furnished or formed with ribs; as, a ribbed cylinder;
      ribbed cloth.
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   2. (Mining) Intercalated with slate; -- said of a seam of
      coal. --Raymond.
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WordNet (r) 3.0 (2006):

ribbed
    adj 1: furnished or strengthened with ribs [ant: ribless]
    2: (of the surface) having a rough, riblike texture [syn:
       costate, ribbed]