Tadpole

Part of speech: noun (n.)

1. 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. The hooded merganser. [Local, U.S.] Tadpole fish. (Zoöl.) See Forkbeard (a).