\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) .