brain

noun
\ˈbrān \

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

Lee is the brain behind hundreds of these characters, many of whom are amazing heroines—and villains, too. Jill Robi, Glamour, "Stan Lee Leaves Behind a Legacy of Powerful Female Characters," 13 Nov. 2018 By the end of class, my arms and core were worn out, and my brain was relieved to get a break. Nicole Tsong, The Seattle Times, "As it turns out, there’s a lot more to hooping than just keeping it at waist level," 29 Oct. 2018 According to the news outlet, she was born with health conditions including an inoperable cyst on her brain, severe scoliosis, and cerebral palsy. Megan Stein, Country Living, "See the Incredible Moment Keith Urban Made a Dying Fan's Last Wish Come True," 20 Oct. 2018 The brain is full of all sorts of strategies that make sense in normal life but can be easily tricked. David Grossman, Popular Mechanics, "This Optical Illusion Will Have Your Brain Rushing To Fill In The Blanks," 11 Oct. 2018 Be sure to follow PCWorld on Facebook, YouTube, Twitch, and Twitter to watch future episodes live and pick our brains in real time! Pcworld Staff, PCWorld, "The Full Nerd ep. 69: Intel's leaked 9000-series, custom RTX performance and when is a deal a deal?," 28 Sep. 2018 One type of ketone flooding the brain is beta-hydroxybutyrate, or BHB. Mark Barna, Discover Magazine, "Not So Fast," 24 Sep. 2018 Plus, the high amounts of omega-3 fatty acids found in some types of fish help reduce your risk of heart disease and stroke and protect your brain. Woman's Day, "Everything You Need to Know About Picking Out and Preparing Fish," 19 Sep. 2018 Beforehand, your brain was all fireworks-worthy fantasies. Yerin Kim, Seventeen, "14 Things No One Tells You About Losing Your Virginity," 22 Aug. 2018

Recent Examples on the Web: Verb

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 But Scotti falls back on the same old, tired, lizard-brained and misogynistic argument that people used against Hillary Clinton: That ambitious women are off-putting. Madeleine Aggeler, The Cut, "When Will We Stop Shaming Ambitious Women?," 5 Jan. 2018 No one knows yet if the man has been identified or if his wife has brained him with a skillet or filed for divorce. Ellie Delano, Woman's Day, "In The Age Of Social Media And Smartphones, No Cheater Is Safe," 11 June 2013

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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Statistics for brain

Last Updated

30 Nov 2018

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

: the ability to think and reason

: a very intelligent person

brain

verb

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

: to hit (someone) on the head very hard

brain

noun
\ˈbrān \

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 \

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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