the Frog, in zoology, a genus belonging to the class of amphibia reptilia. The body is naked, furnished with four feet, and without any tail. There are 17 species. Frogs undergo a very strange metamorphosis. When they first issue from the eggs, they appear in a roundish form, with a long tail, and are then denominated tadpoles. After continuing in this state for several weeks, the tail begins to mortify and fall off gradually, the feet at the same time springing as gradually out of the body, till they assume the complete form of frogs.