brain

1 of 2

noun

1
a
: 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
2
a(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

Illustration of brain

Illustration of brain
  • 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

brain

2 of 2

verb

brained; braining; brains

transitive verb

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

Example Sentences

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.
Recent Examples on the Web
Noun
Matthew Gee, a linebacker on the 1990 Rose Bowl-winning squad, endured an estimated 6,000 hits that caused permanent brain damage and led to cocaine and alcohol abuse that eventually killed him at age 49, lawyers for his widow alleged. Tim Cooper, Arkansas Online, 23 Nov. 2022 Attorneys for Gee said that CTE, which is found in athletes and military veterans who suffered repetitive brain injuries, was an indirect cause of death because head trauma has been shown to promote substance abuse. Brian Melley, ajc, 22 Nov. 2022 Since being hit by a car, Morales has lost movement on the left side of her body, and her speech is delayed and slurred due to the brain injury. Wendy Grossman Kantor, Peoplemag, 22 Nov. 2022 Attorneys for Gee said CTE, which is found in athletes and military veterans who suffered repetitive brain injuries, was an indirect cause of death because head trauma has been shown to promote substance abuse. CBS News, 22 Nov. 2022 Attorneys for Gee said that CTE, which is found in athletes and military veterans who suffered repetitive brain injuries, was an indirect cause of death because head trauma has been shown to promote substance abuse. Brian Melley, Fortune, 22 Nov. 2022 Four years ago, Hall of Fame quarterback Brett Favre joined forces with a Florida neuroscientist to promote an experimental drug — a nasal spray designed to quickly treat brain injuries from a concussion. Laura Strickler, NBC News, 21 Nov. 2022 Those sequences were originally intercut with a scene in which Lynsey tells her doctor about the accident in which her vehicle drove over an explosive device, killing her companion and leaving her with her brain injury. Tyler Coates, The Hollywood Reporter, 21 Nov. 2022 But everything in me, and the logical part of my brain, tells me that love shouldn't feel this way. Patrick Ryan, USA TODAY, 9 Nov. 2022
Verb
The cancer initiative is personal for Biden, who lost his son Beau Biden to brain cancer in 2015. Alexander Thompson, BostonGlobe.com, 11 Sep. 2022 The man who could brain Mr. Lingk with Rusty’s ashes, or the one who could harm and tie up a helpless old lady, would almost certainly be game for something that nasty. Alan Sepinwall, Rolling Stone, 9 Aug. 2022 This can help alleviate back and neck stress and give your eyes and brain a break from the screen. Alexa Mikhail, Fortune, 28 July 2022 They are linked to brain developmental problems in infants and cancer. Katy Stech Ferek, WSJ, 31 Jan. 2022 How will brain stimulation become accessible to all the patients who need it, given how expensive and invasive some treatments are? Isabella Cueto, STAT, 14 Jan. 2022 The researchers contend that this study marks the first time that a machine-learning algorithm has been matched to brain data to explain the workings of a high-level cognitive task. Anna Blaustein, Scientific American, 26 Oct. 2021 Arguably, achieving universal health care and higher education and addressing the nation’s aging water pipe infrastructure (which has yielded a modern-day lead crisis) could be expected to make similar contributions to brain health across decades. Daniel R. George, Scientific American, 25 Aug. 2021 Then of course there’s me, spying on these other women — and some dads, too — instead of keeping tabs on my four kids, one of whom is poised to brain somebody with a stick. Washington Post, 4 June 2021 See More

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.

Word History

Etymology

Noun

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

First Known Use

Noun

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

Verb

14th century, in the meaning defined at sense 1

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

Dictionary Entries Near brain

Cite this Entry

“Brain.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/brain. Accessed 1 Dec. 2022.

Kids Definition

brain 1 of 2

noun

1
a
: the portion of the central nervous system of vertebrate animals that is the organ of thought and the central control point for the nervous system, is enclosed within the skull, and is continuous with the spinal cord
b
: the main nervous center in an invertebrate animal
2
a
: intelligence sense 1
often used in plural
plenty of brains in that family
b
: a very intelligent person
brainlike adjective

brain

2 of 2

verb

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

Medical Definition

brain

noun

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

More from Merriam-Webster on brain

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