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 Maria Menounos is mourning her mother's death who died Sunday after a long battle with stage-four brain cancer. Pamela Avila, USA TODAY, "​​​​​​​'God loved her so much': Maria Menounos pays tribute after mother, Litsa, dies of brain cancer," 3 May 2021 Von became a patient of St. Jude Children's Hospital in January 2019 after having a recurrence of anaplastic ependymoma, a brain cancer. Akeem Glaspie, The Indianapolis Star, "St. Jude patient and cancer survivor Von Rachell will announce Colts second-round pick Friday," 30 Apr. 2021 Nadia Rayan, originally from Lebanon, says the women were a collective source of comfort when Tarek, her 35-year-old son, died of brain cancer five years ago. Rifat Malik, Dallas News, "A ‘powerhouse’ for peace: Janice Lord’s interfaith women’s group looks for common ground," 28 Apr. 2021 The year after Biden lost his 46-year-old son to brain cancer, McConnell called on the Senate to rename a bill aimed at accelerating cancer research after Beau Biden. Kate Sullivan, CNN, "Biden goes off-script to thank McConnell for honoring his late son in 2016," 28 Apr. 2021 Biden helped spearhead the cancer moonshot program under the Obama administration to accelerate the fight against cancer after the death of his son Beau due to brain cancer in 2015. Cassidy Morrison, Washington Examiner, "'I know of nothing that is more bipartisan' than curing cancer, Biden says during joint address," 28 Apr. 2021 Holmes died April 20 after dealing with brain cancer, said Campbell, also a DePaul graduate. Clare Proctor, chicagotribune.com, "After losing podcast co-host to brain cancer, DePaul grad aims to preserve his legacy," 28 Apr. 2021 His death, in the hospice suite of a nursing home, was caused by glioblastoma, an aggressive form of brain cancer, his son, Alec, said. New York Times, "Charles Strum, Versatile Editor for The Times, Dies at 73," 28 Apr. 2021 For the last five years, his lab had been working on a new version of CAR-T therapy, re-engineering human immune cells to attack a particularly deadly form of brain cancer. Megan Molteni, STAT, "Glowing tumor-munching cells, captured on video, show the promise of a new approach to CAR-T cancer therapy," 28 Apr. 2021 Recent Examples on the Web: Verb Biden, who lost his son Beau Biden to brain cancer in 2015, has pledged to make the fight against cancer a key focus of his administration. Dom Calicchio, Fox News, "Biden’s claim that 'dogs may help cure cancer' draws Twitter reactions," 25 Mar. 2021 The priority is personal to Biden, who lost his son Beau Biden to brain cancer in 2015. Marisa Schultz, Fox News, "Biden says once he defeats COVID, cancer is next," 20 Feb. 2021 This less average bone and muscle support makes the head and brain more vulnerable to sudden movement and predicts risk for concussion. Bob Roehr, Scientific American, "Concussions Affect Women More Adversely Than Men," 9 Mar. 2016 To Rio’s distress, a group of boys at a table nearby start to flirt coarsely with the overdeveloped and somewhat under-brained Pucha. Deborah Eisenberg, The New York Review of Books, "Tyrannical Days," 27 May 2020 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

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

6 May 2021

Cite this Entry

“Brain.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/brain. Accessed 10 May. 2021.

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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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