Source : Webster's Revised Unabridged Dictionary (1913)

Tadpole \Tad"pole`\, n. [OE. tadde toad (AS. t[=a]die,
   t[=a]dige) + poll; properly, a toad that is or seems all
   head. See {Toad}, and {Poll}.]
   1. (Zo["o]l.) The young aquatic larva of any amphibian. In
      this stage it breathes by means of external or internal
      gills, is at first destitute of legs, and has a finlike
      tail. Called also {polliwig}, {polliwog}, {porwiggle}, or
      {purwiggy}.

   2. (Zo["o]l.) The hooded merganser. [Local, U. S.]

   {Tadpole fish}. (Zo["o]l.) See {Forkbeard}
      (a) .

Polliwig \Pol"li*wig\, Polliwog \Pol"li*wog\, n. [OE. polwigle.
   Cf. {Poll} head, and {Wiggle}.] (Zo["o]l.)
   A tadpole; -- called also {purwiggy} and {porwigle}.