Any one of numerous species of small rodents belonging to
   the genus Mus and various related genera of the family Muridae. The
   common house mouse (Mus musculus) is found in nearly all countries. The
   American white-footed, or deer, mouse (Hesperomys leucopus) sometimes
   lives in houses. See Dormouse, Meadow mouse, under Meadow, and Harvest
   mouse, under Harvest.