1 brain | Definition of brain

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

Neural networks old and new are based on math inspired by simple models of how neurons function in the brain. Tom Simonite, WIRED, "Ask the Know-It-Alls: How Do Machines Learn?," 26 Aug. 2019 Also important to note: The EEE virus can cause two different types of illness, per the CDC: systemic or encephalitic (which, again, causes inflammation and swelling in the brain). Korin Miller, Health.com, "Eastern Equine Encephalitis Has Reportedly Killed 1 Woman—Here's What to Know About the Mosquito-Borne Disease," 26 Aug. 2019 At seven months old, Kendall Brown was hospitalized with rib fractures and bleeding in his brain. Tim Prudente, baltimoresun.com, "Baltimore man found guilty of killing girlfriend’s baby — the 2nd time he’s been convicted in a child’s death," 26 Aug. 2019 Green was airlifted to a hospital, where bleeding in his brain was discovered. Ken Belson, New York Times, "Touch Football, Sold as Safer, Now Requires a Helmet," 20 Aug. 2019 According to a 2010 study, multiple neural networks in the brain are activated during chewing. Alex Kuczynski, Harper's BAZAAR, "Inside Silicon Valley's Dangerous New Obsession With Fasting," 17 Aug. 2019 After finding a tumor in his brain, doctors at Doernbecher Children’s Hospital were able to successfully remove it. Tim Brown, oregonlive.com, "Nike, Doernbecher reveal 6 patient-designers for 2019 DB Freestyle shoe, clothing collections," 12 Aug. 2019 Or maybe, everything is sort of jumbled in his brain. Finding Joe Murphy, Freep.com, "Joe Murphy, Red Wings' No. 1 pick, is homeless again — and refusing help," 8 Aug. 2019 My posture suffers most when these pick up speed in my brain, swirling into a stress storm. T. Wise, Bon Appétit, "I Thought It’d Be Easy to Fix My Bad Posture—I Was Wrong," 7 Aug. 2019

Recent Examples on the Web: Verb

In many cases, this appears tied to brain abnormalities…. There are different terms and models for assessing such a person. James Fallows, The Atlantic, "On Trump and Queeg: A Followup," 25 Aug. 2019 Long before blows land, the audience is taking inventory of the props, assessing which could be used by one brother to brain or strangle the other. Graeme Wood, The Atlantic, "Sam Shepard Saw It All Coming," 11 July 2019 These structures also raise an ethical question that used to be strictly in the realm of science fiction — can brain organoids become sufficiently advanced to develop consciousness? San Diego Union-Tribune, "Biotech notebook: Cancer discovery, bacterial syringes and organoids," 13 July 2019 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

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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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