Why the Computer Mouse is called so?

The name mouse originated from the resemblance of early models which had a cord attached to the rear part of the device (suggesting the idea of a tail) to the common mouse. - Wikipedia

It's understandable now with wireless mouse features (no tail!), and even the replacement of the traditional mouse for a touch pad (on laptops), it's hard for the new generation of computer users to see the relation.

The name mouse originated at the Stanford Research Institute and derives from the resemblance of early models which had a cord attached to the rear part of the device (suggesting the idea of a tail) to the common mouse.

http://en.wikipedia.org/wiki/Mouse_%28computing%29

Hope this helps!

It is called so because it does work like that,

the real mouse try catching it how does it run, the same way even our P.C mouse runs we can change or move cursor anywhere and at anytime and unlike other applications it wont take time to move from one place to other,

Because of its size and structure