tadpole

n. Larva, esp. Of a frog, toad, or newt. [related to *toad, *poll]

n. 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.