brain

Etymology

From Middle English brayn, brain, from Old English bræġn (“brain”), from Proto-West Germanic *bragn, from Proto-Germanic *bragną (“brain”), from Proto-Indo-European *mregʰnom (“skull, brain”), from Proto-Indo-European *mregʰ- (“marrow, sinciput”) + *-mn̥ (“nominal suffix”). Cognate with Scots braine, brane (“brain”), North Frisian brayen, brein (“brain”), Saterland Frisian Brainge (“brain”), West Frisian brein (“brain”), Dutch brein (“brain”), Low German Brägen, Bregen (“brain”) (whence German Bregen (“animal brain”)), Ancient Greek βρεχμός (brekhmós, “front part of the skull, top of the head”).

noun

1. The control center of the central nervous system of an animal located in the skull which is responsible for perception, cognition, attention, memory, emotion, and action.
   Irregular bedtimes may disrupt healthy brain development in young children, according to a study of intelligence and sleeping habits. ¶ Going to bed at a different time each night affected girls more than boys, but both fared worse on mental tasks than children who had a set bedtime, researchers found. 2013-07-19, Ian Sample, “Irregular bedtimes may affect children's brains”, in The Guardian Weekly, volume 189, number 6, page 34
   1. A part of the brain, especially associated with particular mental functions, abilities, etc.
      The left brain, or that which supplies and animates the right side of the body, is the most active brain, as a general rule. 1892, Benjamin Ward Richardson, The Asclepiad, London, page 357
      What is expressed in the lotus, the plumed serpent, or the staff of Osiris is the yogi's knowledge of the three brains of man. The first brain is the reptilian brain of the spinal cord, the brain of instinctive reflexes, the brain of the subconscious. 1981, William Irwin Thompson, The Time Falling Bodies Take to Light: Mythology, Sexuality and the Origins of Culture, London: Rider/Hutchinson & Co., page 113
2. (informal) An intelligent person.
   She was a total brain.
   Peebee: The brains and I are comparing Remnant notes and filling in the blanks. 2017, BioWare, Mass Effect: Andromeda (Science Fiction), Redwood City: Electronic Arts, →OCLC, PC, scene: Nexus
   1. (plural only) A person who provides the intelligence required for something.
      He is the brains behind the scheme.
3. (in the plural) Intellect.
   "We provided a lot of brains and a lot of heart to the response when it was needed," says Sandra Sanchez, director of AFSC's Immigrants' Voice Program in Des Moines. 2008 Quaker Action (magazine) Rights trampled in rush to deport immigrant workers, Fall 2008, Vol. 89, No. 3, p. 8
   She has a lot of brains.
   1. (in the singular) An intellectual or mental capacity.
      Gerald always acts like he doesn't have a brain.
4. By analogy with a human brain, the part of a machine or computer that performs calculations.
   The computer's brain is capable of millions of calculations a second.
5. (slang, vulgar, uncountable) Oral sex.
   Have you ever popped champagne on a plane, while gettin' some brain? 2007, “Good Life”, in Graduation, performed by Kanye West ft. T-Pain
   You said I got brain from your dame in the range In the passing lane But you really ain't got no proof 2012, Mack Maine featuring Turk and Mystikal, I'm On It
   She giving brain / She eat the dick up like some M&Ms 2018, “Squidrific”, performed by SahBabii
6. (informal, slang) Mind.
   I have too much on my brain today.
7. A loose compartment of a backpack that straps on over the top opening.

verb

1. (transitive) To dash out the brains of; to kill by smashing the skull.
2. (transitive, slang) To strike (someone) on the head.
3. (transitive, figurative) To destroy; to put an end to.
4. (transitive, obsolete) To conceive in the mind; to understand.