Yes, ossa is a Scrabble word!
...and is worth 4 points in Scrabble, and 4 points in Words with Friends
ossa
Noun
1. A mouth or mouthlike opening
2. A hard brittle blue-grey or blue-black metallic element that is one of the platinum metals; the heaviest metal known
3. (computer science) software that controls the execution of computer programs and may provide various services
4. The left eye
5. Rigid connective tissue that makes up the skeleton of vertebrates
What Scrabble words can I make with the letters in ossa?
3 Letter Words
2 Letter Words