Yes, dirt is a Scrabble word!
...and is worth 5 points in Scrabble, and 5 points in Words with Friends
dirt
Adjective
1. (of roads) not leveled or drained; unsuitable for all year travel
Noun
1. The part of the earth's surface consisting of humus and disintegrated rock
2. The state of being covered with unclean things
3. Obscene terms for feces
4. Disgraceful gossip about the private lives of other people
What Scrabble words can I make with the letters in dirt?
3 Letter Words
2 Letter Words