The story
- Proto-Indo-European*per-
- Proto-Indo-European*pr̥h₂-k-yé-ti
- Proto-Hellenic*prā́t͏̌t͏̌ō
- Ancient Greekπρᾱ́σσω (prā́ssō)
- Ancient Greekπρᾱγ- (prāg-)
- Ancient Greekπρακτικός (praktikós)
- Latinprācticus
- Middle Frenchpractique
- Middle Frenchpracticien
- Englishpractician
- English todaypractitioner
Formerly practicioner for *practicianer, from practician + -er (the suffix unnecessarily added, as in musicianer).
Etymology from Wiktionary, CC BY-SA 4.0.