Question

"In the term pyrexia, what is the root word and what does the root word mean?"

Answer 1

Pyrexia mean rise in body temperature. Using your context clue from the word pyro you can guess that Pyr mean fire or heat related.

Answer 2

raised body temperature; fever.

Word Origin and History for pyrexia. n. "fever," 1769, medical Latin, from Greek pyrexis "feverishness," from pyressein "to be feverish, to be ill of fever," from pyretos "fever, burning heat," related to pyr "fire" (see fire (n.)). pyrexia in Medicine.