brain

noun
\ ˈbrān How to pronounce brain (audio) \

Definition of brain

 (Entry 1 of 2)

1a : the portion of the vertebrate central nervous system enclosed in the skull and continuous with the spinal cord through the foramen magnum that is composed of neurons and supporting and nutritive structures (such as glia) and that integrates sensory information from inside and outside the body in controlling autonomic function (such as heartbeat and respiration), in coordinating and directing correlated motor responses, and in the process of learning — compare forebrain, hindbrain, midbrain
b : a nervous center in invertebrates comparable in position and function to the vertebrate brain
2a(1) : intellect, mind has a clever brain
(2) : intellectual endowment : intelligence often used in plural plenty of brains in that family
b(1) : a very intelligent or intellectual person
(2) : the chief planner within a group usually used in plural she's the brains behind their success
3 : something that performs the functions of a brain especially : an automatic device (such as a computer) for control or computation

brain

verb
brained; braining; brains

Definition of brain (Entry 2 of 2)

transitive verb

1 : to kill by smashing the skull
2 : to hit on the head

Illustration of brain

Illustration of brain

Noun

brain 1a: 1 cerebral hemisphere, 2 corpus callosum, 3 ventricle, 4 fornix, 5 thalamus, 6 pituitary gland, 7 pons, 8 medulla oblongata, 9 spinal cord, 10 cerebellum, 11 midbrain

In the meaning defined above

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Examples of brain in a Sentence

Noun

Scientists are learning more about how the human brain works. The left and right sides of the brain have different functions. The other children always teased him about being such a brain.

Verb

The tree limb fell and nearly brained me.
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Recent Examples on the Web: Noun

But upon closer inspection, the patient will be receiving a boost to their brain to help treat depression. Jane Stueckemann, Houston Chronicle, "The Woodlands gets first ketamine infusion center to treat depression," 9 July 2019 Every Monday night, Bon Appétit editor in chief Adam Rapoport gives us a peek inside his brain by taking over our newsletter. Adam Rapoport, Bon Appétit, "Maine Is the Best-Ever Vacation Spot," 9 July 2019 Neuroscientists asked: What’s the difference in their brains? Sigal Samuel, Vox, "How your brain invents morality," 8 July 2019 Doctors at the University of Nebraska Medical Center told police that the baby, named Vera, had been deprived of oxygen for more than 10 minutes, causing severe, life-threatening swelling in her brain. Minyvonne Burke, NBC News, "Unlicensed Nebraska midwife arrested after baby dies following botched home birth," 5 July 2019 Their work raises the possibility that immune system advances in fighting cancer could be duplicated in brain disease. Christopher Rowland, Washington Post, "Alzheimer’s research is getting a reboot at small companies focused on the immune system," 5 July 2019 As with previous movies in the franchise, the key to enjoying it is to mentally wall off the well, actually region of your brain. Jonathan M. Gitlin, Ars Technica, "New Hobbs and Shaw trailer stars a McLaren 720S and Hobbs’ mom," 28 June 2019 Holmes had an enlarged heart and cirrhosis of the liver — both signs of significant pre-existing disease, the Dominican authorities said, and Day also had fluid in her brain. Cnn.com Wire Service, The Mercury News, "FBI assisting Dominican Republic authorities by looking at minibar toxicology samples of US tourists who died," 21 June 2019 For a city trying to keep its economy from turning into a tech monoculture, that seems like a brain-dead move. Owen Thomas, SFChronicle.com, "San Francisco, why are you so taxing?," 19 June 2019

Recent Examples on the Web: Verb

By the 1980s, scientists had figured out that our early ancient relatives were short and small-brained up to about two million years ago. Quanta Magazine, "Scientists Seek to Update Evolution," 22 Nov. 2016 And yet the story rolls on, oblivious and hare-brained. John Anderson, WSJ, "‘The Romanoffs’ Review: Far From Revolutionary," 11 Oct. 2018 According to the study, the ratio of neurons to brain size in most carnivores was nearly equivalent to herbivores. Elly Belle, Teen Vogue, "Study Says Dogs Are Actually Smarter Than Cats," 18 June 2018 Took out Isadora Duncan when her scarf got caught in the spokes of a wheel, decapitated Jayne Mansfield, sprayed John Kennedy’s brains all over his wife. Aaron Gilbreath, Longreads, "The Red Caddy," 24 Apr. 2018 At least 64 people perished during the storm, drowned in their houses or brained by flying debris. The Economist, "America has let down its Puerto Rican citizens," 12 Apr. 2018 Yet if there’s a British stereotype of American English as twangy and slangy, there’s a corresponding American stereotype of British English as quaint and feather-brained. Henry Hitchings, WSJ, "‘The Prodigal Tongue’ Review: More Trouble in the Colonies," 12 Apr. 2018 Today’s condom challenge will morph into tomorrow’s equally hare-brained idea. Heidi Stevens, chicagotribune.com, "Calm down about the condom challenge, grown-ups," 2 Apr. 2018 Many experts believe that maintaining physical fitness can help keep blood flowing normally to brain tissue, which can reduce the risk of damage or deterioration. Amanda Macmillan, Time, "How Exercise May Help Protect Your Brain From Cognitive Decline and Dementia," 16 Feb. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'brain.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of brain

Noun

before the 12th century, in the meaning defined at sense 1a

Verb

14th century, in the meaning defined at sense 1

History and Etymology for brain

Noun

Middle English, from Old English brægen; akin to Middle Low German bregen brain, and perhaps to Greek brechmos front part of the head

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Learn More about brain

Statistics for brain

Last Updated

13 Jul 2019

Look-up Popularity

Time Traveler for brain

The first known use of brain was before the 12th century

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More Definitions for brain

brain

noun

English Language Learners Definition of brain

 (Entry 1 of 2)

: the organ of the body in the head that controls functions, movements, sensations, and thoughts
informal : the ability to think and reason
informal : a very intelligent person

brain

verb

English Language Learners Definition of brain (Entry 2 of 2)

informal : to hit (someone) on the head very hard

brain

noun
\ ˈbrān How to pronounce brain (audio) \

Kids Definition of brain

 (Entry 1 of 2)

1 : the part of the nervous system that is inside the skull, consists of grayish nerve cells and whitish nerve fibers, and is the organ of thought and the central control point for the nervous system
2 : the ability to think : intelligence
3 : someone who is very smart

brain

verb
brained; braining

Kids Definition of brain (Entry 2 of 2)

: to hit on the head very hard

brain

noun
\ ˈbrān How to pronounce brain (audio) \

Medical Definition of brain

1 : the portion of the vertebrate central nervous system enclosed in the skull and continuous with the spinal cord through the foramen magnum that is composed of neurons and supporting and nutritive structures (as glia) and that integrates sensory information from inside and outside the body in controlling autonomic function (as heartbeat and respiration), in coordinating and directing correlated motor responses, and in the process of learning — see forebrain, hindbrain, midbrain
2 : a nervous center in invertebrates comparable in position and function to the vertebrate brain

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More from Merriam-Webster on brain

Rhyming Dictionary: Words that rhyme with brain

Thesaurus: All synonyms and antonyms for brain

Spanish Central: Translation of brain

Nglish: Translation of brain for Spanish Speakers

Britannica English: Translation of brain for Arabic Speakers

Britannica.com: Encyclopedia article about brain

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