Tad″pole′ (?), n. [OE. tadde toad (AS. tādie, tādige) + poll; properly, a toad that is or seems all head. See Toad, and Poll.] 1. (Zoöl.) 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. (Zoöl.) The hooded merganser.
Tadpole fish. (Zoöl.) See Forkbeard (a).