The Collaborative International Dictionary of English v.0.48:

Gag \Gag\, v. t. [imp. & p. p. Gagged; p. pr. & vb. n.
   Gagging.] [Prob. fr. W. cegio to choke or strangle, fr. ceg
   mouth, opening, entrance.]
   1. To stop the mouth of, by thrusting sometimes in, so as to
      hinder speaking; hence, to silence by authority or by
      violence; not to allow freedom of speech to. --Marvell.
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            The time was not yet come when eloquence was to be
            gagged, and reason to be hood winked. --Maccaulay.
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   2. To pry or hold open by means of a gag.
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            Mouths gagged to such a wideness.     --Fortescue
                                                  (Transl.).
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   3. To cause to heave with nausea.
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