Yes, mice is a Scrabble word!

Noun

1. Any of numerous small rodents typically resembling diminutive rats having pointed snouts and small ears on elongated bodies with slender usually hairless tails

2. A swollen bruise caused by a blow to the eye

3. Person who is quiet or timid

4. A hand-operated electronic device that controls the coordinates of a cursor on your computer screen as you move it around on a pad; on the bottom of the device is a ball that rolls on the surface of the pad