The Collaborative International Dictionary of English v.0.48:

Cap \Cap\, v. t. [imp. & p. p. Capped; p. pr. & vb. n.
   Capping.]
   1. To cover with a cap, or as with a cap; to provide with a
      cap or cover; to cover the top or end of; to place a cap
      upon the proper part of; as, to cap a post; to cap a gun.
      [1913 Webster]

            The bones next the joint are capped with a smooth
            cartilaginous substance.              --Derham.
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   2. To deprive of cap. [Obs.] --Spenser.
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   3. To complete; to crown; to bring to the highest point or
      consummation; as, to cap the climax of absurdity.
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   4. To salute by removing the cap. [Slang. Eng.]
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            Tom . . . capped the proctor with the profoundest of
            bows.                                 --Thackeray.
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   5. To match; to mate in contest; to furnish a complement to;
      as, to cap text; to cap proverbs. --Shak.
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            Now I have him under girdle I'll cap verses with him
            to the end of the chapter.            --Dryden.
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   Note: In capping verses, when one quotes a verse another must
         cap it by quoting one beginning with the last letter of
         the first letter, or with the first letter of the last
         word, or ending with a rhyming word, or by applying any
         other arbitrary rule may be agreed upon.
         [1913 Webster]

WordNet (r) 3.0 (2006):

capped
    adj 1: used especially of front teeth having (artificial)
           crowns; "capped teeth gave her a beautiful smile"
    2: covered as if with a cap or crown especially of a specified
       kind; "cloud-capped mountains"; "brown-capped mushrooms";
       "snow-capped peaks"