πυρετός, -οῦ, ὁ (< πῦρ) [in LXX: Deu.28:22 (קַדַּחַת) * ;] a fever: Refs Mat.8:15, Mrk.1:31, Luk.4:39, Jhn.4:52, Act.28:8; π. μέγας, a high fever: Luk.4:38 (on the technical phrase here, see MM, xxii).† (AS)
Thayer:
1) fiery heat 2) fever
πυρετός
puretos
poo-ret-os'
From G4445; inflamed, that is, (by implication) feverish (as noun, fever)