noun
field mouse; meadow mouse
Refers to small wild mice living in fields or meadows, as opposed to house mice.
秋になると野ねずみが畑にたくさん現れる。
In autumn, many field mice appear in the fields.
野ねずみは冬に備えて食べ物をため込む。
Field mice store up food in preparation for winter.
ハツカネズミ specifically refers to the house mouse (Mus musculus), while 野ねずみ is a broader term for wild mice found outdoors.
Compound of 野 (の, 'field') and 鼠 (ねずみ, 'mouse'). The reading is a straightforward combination of the kun'yomi readings.