Yes, quad is a Scrabble word!
...and is worth 14 points in Scrabble, and 15 points in Words with Friends
quad
Noun
1. One of four children born at the same time from the same pregnancy
2. A muscle of the thigh that extends the leg
3. (printing) a block of type without a raised letter; used for spacing between words or sentences
4. A rectangular area surrounded on all sides by buildings
What Scrabble words can I make with the letters in quad?
3 Letter Words
2 Letter Words