brain
[breyn]
| 1. | Anatomy, Zoology. the part of the central nervous system enclosed in the cranium of humans and other vertebrates, consisting of a soft, convoluted mass of gray and white matter and serving to control and coordinate the mental and physical actions. |
| 2. | Zoology. (in many invertebrates) a part of the nervous system more or less corresponding to the brain of vertebrates. |
| 3. | Sometimes, brains. (used with a plural verb ) understanding; intellectual power; intelligence. |
| 4. | the brain as the center of thought, understanding, etc.; mind; intellect. |
| 5. | brains, Slang. a member of a group who is regarded as its intellectual leader or planner: The junior partner is the brains of the firm. |
| 6. | Informal. a very intelligent or brilliant person. |
| 7. | Informal.
|
| 8. | to smash the skull of. |
| 9. | Slang. to hit or bang (someone) on the head. |
| 10. | beat one's brains out, Informal. to try very hard to understand and work out a problem, remember something, etc.: She beat her brains out studying for the exam. |
| 11. | have something on the brain, to have an obsession; be occupied with: Lately I seem to have food on the brain. |
| 12. | pick someone's brains, to obtain information by questioning another person rather than by seeking it independently: He refused to prepare for the exam but counted on being able to pick his roommate's brains. |
bef. 1000; ME; OE bræg(e)n, bregen; c. LG brägen, D brein

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Based on the Random House Dictionary, © Random House, Inc. 2009.
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brain (brān) ![]() (click for larger image in new window) n.
[Middle English, from Old English brægen.] |
Copyright © 2009 by Houghton Mifflin Company.
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Brain
Brain\, n. [OE. brain, brein, AS. bragen, br[ae]gen; akin to LG. br["a]gen, bregen, D. brein, and perh. to Gr. ?, the upper part of head, if ? =?. [root]95.]1. (Anat.) The whitish mass of soft matter (the center of the nervous system, and the seat of consciousness and volition) which is inclosed in the cartilaginous or bony cranium of vertebrate animals. It is simply the anterior termination of the spinal cord, and is developed from three embryonic vesicles, whose cavities are connected with the central canal of the cord; the cavities of the vesicles become the central cavities, or ventricles, and the walls thicken unequally and become the three segments, the fore-, mid-, and hind-brain. Note: In the brain of man the cerebral lobes, or largest part of the forebrain, are enormously developed so as to overhang the cerebellum, the great lobe of the hindbrain, and completely cover the lobes of the midbrain. The surface of the cerebrum is divided into irregular ridges, or convolutions, separated by grooves (the so-called fissures and sulci), and the two hemispheres are connected at the bottom of the longitudinal fissure by a great transverse band of nervous matter, the corpus callosum, while the two halves of the cerebellum are connected on the under side of the brain by the bridge, or pons Varolii. 2. (Zo["o]l.) The anterior or cephalic ganglion in insects and other invertebrates. 3. The organ or seat of intellect; hence, the understanding. " My brain is too dull." --Sir W. Scott. Note: In this sense, often used in the plural. 4. The affections; fancy; imagination. [R.] --Shak. To have on the brain, to have constantly in one's thoughts, as a sort of monomania. [Low] Brain box or case, the bony on cartilaginous case inclosing the brain. Brain coral, Brain stone coral (Zo["o]l), a massive reef-building coral having the surface covered by ridges separated by furrows so as to resemble somewhat the surface of the brain, esp. such corals of the genera M[ae]andrina and Diploria. Brain fag (Med.), brain weariness. See Cerebropathy. Brain fever (Med.), fever in which the brain is specially affected; any acute cerebral affection attended by fever. Brain sand, calcareous matter found in the pineal gland.Brain
Brain\, v. t. [imp. & p. p. Brained; p. pr. & vb. n. Braining.]1. To dash out the brains of; to kill by beating out the brains. Hence, Fig.: To destroy; to put an end to; to defeat. There thou mayst brain him. --Shak. It was the swift celerity of the death . . . That brained my purpose. --Shak. 2. To conceive; to understand. [Obs.] ?T is still a dream, or else such stuff as madmen Tongue, and brain not. --Shak.Cite This Source
brain
The central organ in the nervous system, protected by the skull. The brain consists of the medulla, which sends signals from the spinal cord to the rest of the brain and also controls the autonomic nervous system; the pons, a mass of nerve fibers connected to the medulla; the cerebellum, which controls balance and coordination; and the cerebrum, the outer layer of which, the cerebral cortex, is the location of memory, sight, speech, and other higher functions.
The cerebrum contains two hemispheres (the left hemisphere and the right hemisphere), each of which controls different functions. In general, the right hemisphere controls the left side of the body and such functions as spatial perception, whereas the left hemisphere controls the right side of the body and functions such as speech.
Under the cerebral cortex are the thalamus, the main relay center between the medulla and the cerebrum; and the hypothalamus, which controls blood pressure, body temperature, hunger, thirst, sex drive, and other visceral functions.
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brain
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Main Entry: brain
Pronunciation: 'brAn
Function: noun
1 : the portion of the vertebrate central nervous system that constitutes the organ of thoughtand neural coordination, includes all the higher nervous centers receiving stimuli from the sense organs and interpreting and correlating them to formulate the motor impulses, is made up of neurons andsupporting and nutritive structures, is enclosed within the skull, and is continuous with the spinal cord through the foramen magnum
2 : a nervous center in invertebratescomparable in position and function to the vertebrate brain
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brain (brān)
n.
The portion of the central nervous system that is enclosed within the cranium, continuous with the spinal cord, and composed of gray matter and white matter. It is the primary center for the regulation and control of bodily activities, receiving and interpreting sensory impulses, and transmitting information to the muscles and body organs. It is also the seat of consciousness, thought, memory, and emotion. Also called encephalon.
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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brain (brān) Pronunciation Key
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Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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brain
In addition to the idioms beginning with brain, also see beat one's brains out; blow one's brains out; on one's mind (the brain); pick someone's brains; rack one's brains.
Copyright © 1997. Published by Houghton Mifflin.
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