A — 1: πυρετός
(Strong's #4446 — Noun Masculine — puretos — poo-ret-os' )

"feverish heat" (from pur, "fire"), hence, "a fever," occurs in Matthew 8:15; Mark 1:31; John 4:52; Acts 28:8; in Luke 4:38 , with megas, "great, a high fever;" ver. 39. Luke, as a physician, uses the medical distinction by which the ancients classified fevers into great and little. In the Sept., Deuteronomy 28:22 .

B — 1: πυρέσσω
(Strong's #4445 — Verb — puresso — poo-res'-so )

signifies "to be ill of a fever" (akin to A), Matthew 8:14; Mark 1:30 .