1

brain

noun \ ˈbrān \

Definition of brain

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

Examples of brain in a Sentence

  1. Scientists are learning more about how the human brain works.

  2. The left and right sides of the brain have different functions.

  3. The other children always teased him about being such a brain.

Recent Examples of brain from the Web

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.

Illustration of brain

Origin and Etymology of brain

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


2

brain

verb

Definition of brain

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

Examples of brain in a Sentence

  1. The tree limb fell and nearly brained me.

Recent Examples of brain from the Web

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.

First Known Use of brain

14th century



BRAIN Defined for English Language Learners

brain

noun

Definition of brain for English Language Learners

  • : 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

Definition of brain for English Language Learners

  • : to hit (someone) on the head very hard


BRAIN Defined for Kids

1

brain

noun \ ˈbrān \

Definition of brain for Students

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

2

brain

verb

Definition of brain for Students

brained; braining
:to hit on the head very hard

Medical Dictionary

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

Illustration of brain



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