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

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.
Recent Examples on the Web
Noun
Nine months after brain surgery from a football injury, Santa Cruz ran the anchor leg in the 4x400 relay to help his team take second at last year’s finals. Steve Galluzzo, Los Angeles Times, 11 May 2024 Joined by wife Gwen Stefani plus actors and musicians from country, pop Broadway and beyond, Shelton helped raise awareness and funds for the Cleveland Clinic Lou Ruvo Center for Brain Health, which in part funds and facilitates research into brain disorders including Alzheimer's and Parkinson's. Kate Hogan, Peoplemag, 11 May 2024 See all Example Sentences for brain 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'brain.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

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 21 May. 2024.

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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