Merriam-Webster's Word of the Day for January 2, 2026 is:

febrile • \FEB-ryle\  • adjective

Febrile is a medical term meaning "marked or caused by fever; feverish." It is sometimes used figuratively, as in "a febrile political climate."

// I'm finally back on my feet after recovering from a febrile illness.

// The actor delivered the monologue with a febrile intensity.

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Examples:

"Peppered with exclamation marks, breathless and febrile, this is an utterly mesmeric account of how one man's crimes can affect an entire community." — Laura Wilson, The Guardian (London), 20 June 2025

Did you know?

The English language has had the word fever for as long as the language has existed (that is, about a thousand years); the related adjective feverish has been around since the 14th century. But that didn’t stop the 17th-century medical reformer Noah Biggs from admonishing physicians to care for their "febrile patients" properly. Biggs apparently thought his medical writing required a word that clearly nodded to a Latin heritage, and called upon the Latin adjective febrilis, from febris, meaning "fever." It’s a tradition that English has long kept: look to Latin for words that sound technical or elevated. But fever too comes from febris. It first appeared (albeit with a different spelling) in an Old English translation of a book about the medicinal qualities of various plants. By Biggs’s time it had shed all obvious hallmarks of its Latin ancestry. Febrile, meanwhile, continues to be used in medicine in a variety of ways, including in references to such things as "febrile seizures" and "the febrile phase" of an illness. The word has also developed figurative applications matching those of feverish, as in "a febrile atmosphere."