Learner's definition of MOUSE
1 : a very small animal that has a pointed nose and a long, thin tail
— sometimes used figuratively to refer to a weak, frightened, or quiet person
The house was infested with mice and rats.
a field mouse [=a type of mouse that lives in fields]
a house mouse [=a type of mouse that lives in people's houses]
plural alsomouses: a small device that is connected to a computer and that you move with your hand to control the movement of a pointer on the computer screen