Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Medical
  • Scrabble
  • Spanish Central
  • Learner's Dictionary

Medical Dictionary

blood–brain barrier

noun

Medical Definition of blood–brain barrier

  1. :  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




Seen and Heard

What made you want to look up blood–brain barrier? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

February 11, 2016

the holder of an office

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

image33683556

How much does a batman (the Turkish unit of measurement) weigh?

100 pounds 196.5 pounds 16.96 pounds 2.2 pounds
Name That Thing

10 quick questions: hear them, spell them, and see how your skills compare to the crowd.

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ