Real Dictionary

mouse
countable noun: A mouse is a small furry animal with a long tail.

mouse in American English
any of a large number of small, widespread rodents belonging to various families and having small ears and a long, thin tail, esp., a species ( Mus musculus) that commonly infests buildings
to hunt for
intransitive verb: to hunt for or catch mice
noun: any of numerous small Old World rodents of the family Muridae, esp. of the genus Mus, introduced widely in other parts of the world
transitive verb: to hunt out, as a cat hunts out mice

mouse in British English
noun: any of numerous small long-tailed rodents of the families Muridae and Cricetidae that are similar to but smaller than rats