“Aṭṭī” means bones. Aṭṭīyati means for a person to consider mind-leasing things as useless as a dog wasting time chewing on a bone.
In the plural, it is “aṭṭīyeyyātha”:
Devaloka Sutta
“Aṭṭīyāmi” is “I consider ..”:
Vijayā Sutta
A Quest to Recover Buddha's True Teachings