febrile

adjective

fe·​brile ˈfe-ˌbrī(-ə)l 

also

ˈfē- 

: marked or caused by fever : feverish

a febrile reaction caused by an allergy

Did you know?

Not too surprisingly, febrile originated in the field of medicine. We note its first use in the work of the 17th-century medical reformer Noah Biggs. Biggs used it in admonishing physicians to care for their "febrile patients" properly. Both feverish and febrile are from the Latin word for "fever," which is febris. Nowadays, febrile is used in medicine in a variety of ways, including references to such things as "the febrile phase" of an illness. And, like feverish, it also has an extended sense, as in "a febrile emotional state."

Examples of febrile in a Sentence

Recent Examples on the Web

There is a small but increased risk of febrile seizure when the MMRV combination is given as the first dose, so the CDC had already recommended that the varicella vaccine be given separately for children under 4. —Meg Tirrell, CNN Money, 6 Oct. 2025

This change helps lower the chance of a febrile seizure, which can happen more often with the combo vaccine. —Sherri Gordon, Parents, 26 Sep. 2025

The vaccine is associated with a slight increase in the risk of febrile seizures, but it is administered to only a small percentage of children each year, and children will still be able to receive other vaccinations for the infections that M.M.R.V. covers. —Dhruv Khullar, New Yorker, 24 Sep. 2025

Kids with flu also can develop brain inflammation as well as febrile and non-febrile seizures. —Dr. Kristina Bryant, Boston Herald, 21 Sep. 2025

Word History

Etymology

Medieval Latin febrilis, from Latin febris fever

First Known Use

1651, in the meaning defined above

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Medical Definition

febrile

adjective

fe·​brile

ˈfeb-ˌrīl also ˈfēb-

: marked or caused by fever : feverish