ague

The story

1. Latin · derived fromacūtus“sharp, acute”
2. Middle English · inherited fromagu
3. English todayague

From Middle English agu, ague, borrowed from Middle French (fievre) aguë, “acute (fever)” (Modern French fièvre aiguë), from Late Latin (febris) acuta (“acute fever”), from Latin acūtus (“sharp, acute”) + febris (“fever”). Doublet of acute.