Parsley goes back through English and Latin forms to Greek petroselinon, a compound of petros, stone, and selinon, celery.
The Vulgar Latin stage is reconstructed, conventionally *petrosilium. Its spelling is a scholarly reconstruction rather than a directly attested form; that status is revealed with the language labels.
Sources
- Merriam-Webster: parsley
Word History gives the complete selected route, marks *petrosilium as reconstructed, and explains the Greek stone/celery elements.
- Bosworth-Toller Anglo-Saxon Dictionary · search
Meanings of the older forms on the word path.
- logeion.uchicago.edu · petroselinum
Meanings of the older forms on the word path.
- Online Etymology Dictionary · parsley
Meanings of the older forms on the word path.
- logeion.uchicago.edu · πετροσέλινον
Meanings of the older forms on the word path.