The Collaborative International Dictionary of English v.0.48:

Waddle \Wad"dle\, v. i. [imp. & p. p. Waddled; p. pr. & vb. n.
   Waddling.] [Freq. of wade; cf. AS. w[ae]dlian to beg, from
   wadan to go. See Wade.]
   To walk with short steps, swaying the body from one side to
   the other, like a duck or very fat person; to move clumsily
   and totteringly along; to toddle; to stumble; as, a child
   waddles when he begins to walk; a goose waddles. --Shak.
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         She drawls her words, and waddles in her pace. --Young.
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