blood-brain barrier

noun

ˈbləd-ˈbrān- 

: a naturally occurring barrier created by the modification of brain capillaries (as by reduction in fenestration and formation of tight cell-to-cell contacts) that prevents many substances from leaving the blood and crossing the capillary walls into the brain tissues

Examples of blood-brain barrier in a Sentence

Recent Examples on the Web

Many of these compounds can cross the blood-brain barrier and help to fight inflammation and oxidative stress, both of which can damage cells and are linked to dementia. —Dana G. Smith, New York Times, 6 Jan. 2026

In a small clinical trial in New York, pediatric oncologists harnessed the technology to temporarily—but repeatedly—open the blood-brain barrier in three children with a rare type of brain cancer called diffuse midline glioma. —IEEE Spectrum, 19 Nov. 2025

Inflammatory molecules can cross the blood-brain barrier and cause damage to the brain. —Sarah Bence, Verywell Health, 6 Nov. 2025

Because these ultra-small devices are fused with living biological cells before injection, they are not rejected by the immune system and can cross the blood-brain barrier naturally, a key advantage over conventional implants that require invasive access. —Neetika Walter, Interesting Engineering, 5 Nov. 2025

Word History

First Known Use

1934, in the meaning defined above

Rhymes for blood-brain barrier

• noncarrier
• carrier

Medical Definition

blood-brain barrier

noun

: a naturally occurring barrier created by the modification of brain capillaries (as by reduction in fenestration and formation of tight cell-to-cell contacts) that prevents many substances from leaving the blood and crossing the capillary walls into the brain tissues

—abbreviation BBB