The spelling of the word "Feveret" may seem unusual, but it can be explained using IPA phonetic transcription. The first syllable, "fev," sounds like the word "fever" with a short "e" sound. The second syllable, "eret," is pronounced "uh-ret," with a schwa sound for the first vowel and a short "e" sound for the second. Overall, "Feveret" is pronounced "FEV-uh-ret," which may be helpful to remember when encountering this word in the future.
A slight fever.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.