The Collaborative International Dictionary of English v.0.48:

Polliwig \Pol"li*wig\, Polliwog \Pol"li*wog\, n. [OE. polwigle.
   Cf. Poll head, and Wiggle.] (Zool.)
   A tadpole; -- called also purwiggy and porwigle.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

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. (Zool.) 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.
      [1913 Webster]

   2. (Zool.) The hooded merganser. [Local, U. S.]
      [1913 Webster]

   Tadpole fish. (Zool.) See Forkbeard
      (a) .
          [1913 Webster]