The story
- Latin · derived fromquartāna
- Old French · derived fromquartaine
- Anglo-Norman · derived fromquartaine
- English todayquartan
From Anglo-Norman quartaine, Old French quartaine, from Latin quartāna (short for febris quartana), noun use of feminine form of quartānus (“recurring every four days”), from quartus (“fourth”).
Etymology from Wiktionary, CC BY-SA 4.0.