Yes, onset is a Scrabble word!
...and is worth 5 points in Scrabble, and 6 points in Words with Friends
onset
Noun
1. The beginning or early stages
2. (military) an offensive against an enemy (using weapons)
What Scrabble words can I make with the letters in onset?
5 Letter Words
4 Letter Words
Sponsored Links
3 Letter Words
2 Letter Words