ague comes from Middle English ague, from Old French (fievre) ague ('acute fever'), from Latin (febris) acūta ('sharp fever'), feminine of acūtus ('sharp, pointed'). The path is chiefly one of transmission: an older form is taken into English, with the word's shape and meaning carried through the language names and forms preserved in the history. In modern use, the noun sense is "a fever marked by recurring chills and shivering, often malarial", which keeps the etymology connected to the word's present dictionary value rather than treating it as a merely historical label. The wider word family includes related English forms such as acute and derivatives such as aguish, showing how the same base continues to support neighboring English vocabulary. The principal historical forms in the chain include Old French ague, Latin acūta, Proto-Indo-European *h₂eḱ-, which anchor the explanation in named linguistic material.