1. A family of the order Rodentia containing 250 genera including the two genera Mus (mice) and Rattus (rats): The Muridae are distributed throughout the world in the tropical and subtropical forests and even in the polar regions.

There are about 450 species of Muridae living in different areas of the world some of which may be terrestrial, arboreal (tree), or semiaquatic; and most of them are herbivorous or insectivorous.

2. Etymology: from the Latin mus and muris, "mouse".