fever

American  

[fee-ver] / ˈfi vər /

noun

1. an abnormal condition of the body, characterized by undue rise in temperature, quickening of the pulse, and disturbance of various body functions.

2. an abnormally high body temperature.

3. the number of degrees of such a temperature above the normal.

4. any of a group of diseases in which high temperature is a prominent symptom.

   scarlet fever.

5. intense nervous excitement.

   The audience was in a fever of anticipation.

---

verb (used with object)

1. to affect with or as with fever.

   The excitement fevered him.

fever British  

/ ˈfiːvə /

noun

1. an abnormally high body temperature, accompanied by a fast pulse rate, dry skin, etc

2. any of various diseases, such as yellow fever or scarlet fever, characterized by a high temperature

3. intense nervous excitement or agitation

   she was in a fever about her party

---

verb

1. (tr) to affect with or as if with fever

fever Scientific  

/ fē′vər /

1. A body temperature that is higher than normal. Fever is the body's natural response to the release of substances called pyrogens by infectious agents such as bacteria and viruses. The pyrogens stimulate the hypothalamus in the brain to conserve heat and increase the basal metabolic rate.

---

fever Idioms  

1. see cabin fever; run a fever.

---

Other Word Forms

• fevered
  adjective
• feverless
  adjective
• unfevered
  adjective

Etymology

Origin of fever

First recorded before 1000; Middle English; Old English fefer, from Latin febr-, stem of febris; reinforced by Anglo-French fevre, Old French fievre, from Latin, as above

Explanation

A fever happens when the body's internal temperature is higher than normal. If you have a sore throat, a headache, and a fever, you may have the flu. When you have a fever, your skin may feel hot, and your temperature as measured by a thermometer will be high. A fever can also make you feel achy, tired, and chilly, and it can be a sign that you've got some kind of infection. The Old English is fefor, from a Latin root, febris, also "fever." Doctors and nurses sometimes refer to a fever as a "febrile response."

Example Sentences

The World Health Organization has declared the outbreak of the highly contagious haemorrhagic fever an international emergency.

From Barron's • May 23, 2026

They wrote about their worries, regrets, doubts, divorce, financial straits—being down to $35 in a checking and savings account—and a baby’s 104-degree fever.

From The Wall Street Journal • May 23, 2026

Early symptoms resemble those of other, more common diseases: fever, fatigue, muscle pain, headache and sore throat.

From The Wall Street Journal • May 22, 2026

The WHO has declared the surge of the highly contagious haemorrhagic fever an international health emergency and will hold an emergency meeting on the crisis on Tuesday.

From Barron's • May 19, 2026

Later that year, Mother Peggy Fox died of typhoid fever and was buried in the Underhill family plot in Brooklyn.

From "American Spirits" by Barb Rosenstock

Related Words

• delirium
• frenzy
• turmoil