brain fog

noun

: a usually temporary state of diminished mental capacity marked by inability to concentrate or to think or reason clearly

Examples of brain fog in a Sentence

Recent Examples on the Web

Pasadena Fire Captain Matt Caffey, also a paramedic for 28 years, helped fight last year’s Eaton fire in Southern California and said the smoke exposure from burning neighborhoods brings on coughing, vomiting and brain fog. — ABC News, 23 Aug. 2026

From anger to brain fog, these issues can seriously disrupt people’s lives. — Jennifer Fields, Washington Post, 23 Aug. 2026

Key Takeaways Iron deficiency can occur without anemia and may cause symptoms such as fatigue and brain fog. — Teresa Maalouf, Verywell Health, 21 Aug. 2026

Plus, dehydration can also worsen other menopause symptoms, including brain fog, fatigue and achy joints. — Maggie Ryan, Flow Space, 20 Aug. 2026

Word History

First Known Use

1853, in the meaning defined above

Rhymes for brain fog

• agog
• backlog
• bulldog
• bullfrog
• eclogue
• eggnog
• groundhog
• hedgehog
• leapfrog
• prolog
• sheepdog
• watchdog

Medical Definition

brain fog

noun

: a usually temporary state of diminished mental capacity marked by inability to concentrate or to think or reason clearly

This brain fog can be a result of being overly stressed, tired, carrying extra weight, consuming too many calories or consistently consuming a diet poor in nutrients.

—Kylie Helgens, The Gazette (Cedar Rapids, Iowa)