: a mouse that frequents houses; especially: a common nearly cosmopolitan grayish-brown mouse of the genus Mus (M. musculus) that lives and breeds about buildings, is an important laboratory animal, and is an important pest as a consumer of human food and as a vector of diseases
Common mouse species (Mus musculus, family Muridae), the mouse most often encountered in buildings. The house mouse has been distributed by humans from Eurasia to all inhabited areas of the world and usually seeks shelter and food in human dwellings. Brown or gray, it grows up to 8 in. (20 cm) long, including a 4-in. (10-cm) tail. It consumes almost anything edible, even sampling soap, paste, and glue. It matures quickly and is ready to mate two to three months after birth. In warm areas or heated buildings, it breeds throughout the year.