brain
n. countablen. the organ inside your head that controls how you think, feel, and move. It acts like a computer for your body, processing everything you see and hear.
n. the primary organ of the central nervous system, responsible for processing sensory information and coordinating physical and cognitive functions.
The brain needs plenty of sleep to function well.
Scientists are still working to understand how the human brain stores long-term memories.
Neuroplasticity allows the brain to reorganize its neural pathways in response to new experiences or after a traumatic injury.
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 (“brain”), Saterland Frisian Brainge, Bräienge (“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”).
Often used figuratively in the plural ('brains') to refer to intelligence or the person responsible for a plan.