Yes, dit is a Scrabble word!
...and is worth 4 points in Scrabble, and 4 points in Words with Friends
dit
Noun
1. The shorter of the two telegraphic signals used in Morse code
What Scrabble words can I make with the letters in dit?
2 Letter Words
Noun
1. The shorter of the two telegraphic signals used in Morse code
2 Letter Words