The Collaborative International Dictionary of English v.0.48:

Applaud \Ap*plaud"\, v. t. [imp. & p. p. Applauded; p. pr. &
   vb. n. Applauding.] [L. applaudere; ad + plaudere to clash,
   to clap the hands: cf. F. applaudir. Cf. Explode.]
   1. To show approval of by clapping the hands, acclamation, or
      other significant sign.
      [1913 Webster]

            I would applaud thee to the very echo,
            That should applaud again.            --Shak.
      [1913 Webster]

   2. To praise by words; to express approbation of; to commend;
      to approve.
      [1913 Webster]

            By the gods, I do applaud his courage. --Shak.
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   Syn: To praise; extol; commend; cry up; magnify; approve. See
        Praise.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Applaud \Ap*plaud"\, v. i.
   To express approbation loudly or significantly.
   [1913 Webster]

WordNet (r) 3.0 (2006):

applaud
    v 1: clap one's hands or shout after performances to indicate
         approval [syn: applaud, clap, spat, acclaim] [ant:
         boo, hiss]
    2: express approval of; "I applaud your efforts"