Yes, inion is a Scrabble word!
...and is worth 5 points in Scrabble, and 7 points in Words with Friends
inion
Noun
1. The craniometric point that is the most prominent point at the back of the head (at the occipital protuberance)
What Scrabble words can I make with the letters in inion?
3 Letter Words
2 Letter Words