Yes, lax is a Scrabble word!
...and is worth 10 points in Scrabble, and 11 points in Words with Friends
lax
Adjective
1. Lacking in rigor or strictness
2. Pronounced with muscles of the tongue and jaw relatively relaxed (e.g., the vowel sound in `bet')
3. Lacking in strength or firmness or resilience
4. Emptying easily or excessively
What Scrabble words can I make with the letters in lax?
2 Letter Words