Yes, nit is a Scrabble word!
...and is worth 3 points in Scrabble, and 4 points in Words with Friends
nit
Noun
1. A luminance unit equal to 1 candle per square meter measured perpendicular to the rays from the source
2. Egg or young of an insect parasitic on mammals especially a sucking louse; often attached to a hair or item of clothing
What Scrabble words can I make with the letters in nit?
3 Letter Words
2 Letter Words