Lexical Definition

‎πυρετός‎ pyretós (poo-ret-os') fever ^G:N-M
from ‎πυρέσσω‎

fever.

• inflamed, i.e. (by implication) feverish (as noun, fever)

Abbott-Smith

πυρετός, -οῦ, ὁ (< πῦρ), [in LXX: De 28:22 (קדַּחַת)*;]
a fever: Mt 8:15, Mk 1:31, Lk 4:39, Jo 4:52, Ac 28:8; π. μέγας, a high fever: Lk 4:38 (on the technical phrase here, v. MM, xxii).†

Abbott-Smith References

Liddell-Scott-Jones

πυρετός-ός, ὁ,

(πῦρ) burning heat, fiery heat, φέρει πυρετὸν δειλοῖσι βροτοῖσιν (i.e. Sirius) [Refs 8th c.BC+]

__II fever, [Refs 5th c.BC+]; θνήσκειν ἐκ π. [Refs]; π. ἀμφημερινοί, τριταῖοι, τεταρταῖοι, quotidian, tertian, quartan fevers, [Refs 5th c.BC+]