The story
- Vulgar Latin · derived from*extonare
- Old French · derived fromestonner
- English todayastonied
Apparently from astony, astonie, from Old French estonner, from Vulgar Latin *extonare. Compare English astonish, of which this was claimed in olden sources to be the more "correct" (or at least Biblical) version of the word.
Etymology from Wiktionary, CC BY-SA 4.0.