Yes, dado is a Scrabble word!
...and is worth 6 points in Scrabble, and 6 points in Words with Friends
dado
Verb
1. Provide with a dado
2. Cut a dado into or fit into a dado
Noun
1. Panel forming the lower part of an interior wall when it is finished differently from the rest of the wall
2. The section of a pedestal between the base and the surbase
3. A rectangular groove cut into a board so that another piece can fit into it
What Scrabble words can I make with the letters in dado?
3 Letter Words
2 Letter Words