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 pluralplenty of brains in that family
b(1) : a very intelligent or intellectual person
(2) : the chief planner within a group usually used in pluralshe'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 In a legal world of high intellects, Starmer’s first-rate brain stood out, but so too did his commitment to the protesters and activists fighting the powerful during Margaret Thatcher’s decade of Tory rule. Olivia Konotey-ahulu, Bloomberg.com, "U.K. Labour Picks ‘Safe’ Keir Starmer as a Life-Raft in a Storm," 10 May 2020 Psychologists prefer to make sense of it through the brain. Arielle Pardes, Wired, "There Are No Hours or Days in Coronatime," 8 May 2020 One of his two sons was stricken with a brain tumor and died in 2015. Chris Megerian, Los Angeles Times, "Trump rarely shows empathy in coronavirus crisis," 4 May 2020 One case in Washington state gained national attention last summer, when two women caught on a doorbell camera stealing packages returned them after learning one contained a gift meant for an autistic boy with a brain tumor. Jessica Flores, USA TODAY, "Women dressed as nurses amid coronavirus pandemic are stealing packages off porches in Washington state, police say," 3 May 2020 Lloyd's agent did not provide details on the cause, but the actor was diagnosed with a brain tumor and cancer last year that had spread to his lungs and spine. Tim O'donnell, TheWeek, "10 things you need to know today: May 2, 2020," 2 May 2020 In January 2019, Lloyd was diagnosed with an inoperable brain tumor and cancer, which eventually spread to his lungs, jaw, liver and spine. NBC News, "'Scrubs' actor Sam Lloyd dies at 56," 2 May 2020 The Vermont native had been diagnosed with an inoperable brain tumor last year, which was revealed in a GoFundMe campaign launched by Scrubs producer Tom Hobert and his wife, Jill. Sharareh Drury, The Hollywood Reporter, "'Scrubs' Actor Sam Lloyd Dies at 56," 2 May 2020 In January 2019, Lloyd was diagnosed with cancer, after doctors discovered an inoperable brain tumor that had metastasized from his lungs. Maureen Lee Lenker, EW.com, "Scrubs and Cougar Town actor Sam Lloyd dies at 56," 1 May 2020 Recent Examples on the Web: Verb The people who can make an outsized difference bring a combination of what is conventionally known as left-brained and right-brained thinking. Quartz India, "Kunal Shah on the jobs that will define India’s future," 11 Feb. 2020 This has meant keeping the games going even as the league faced everything from domestic abuse cases to brain injuries. Jason Parham, WIRED, "Depth of Field: Where Is Jay-Z Taking the NFL?," 15 Aug. 2019 The yawning space between is echoed by an endless lateral runway that makes every entrance and exit seem like a trek and requires the actors to duck their heads to avoid getting brained on the way out. David Rooney, The Hollywood Reporter, "'The Rose Tattoo': Theater Review," 16 Oct. 2019 Yet focusing on chicken shops is not completely bird-brained. The Economist, "A British anti-knife drive comes home to roost," 22 Aug. 2019 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

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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Time Traveler for brain

Time Traveler

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

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Statistics for brain

Last Updated

17 May 2020

Cite this Entry

“Brain.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/brain. Accessed 27 May. 2020.

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More Definitions for brain

brain

noun
How to pronounce brain (audio)

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

Thesaurus: All synonyms and antonyms for brain

Rhyming Dictionary: Words that rhyme with 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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