1. Mind, intellect, intelligence refer to mental equipment or qualities. Mind is that part of a human being that thinks, feels, and wills, as contrasted with body: His mind was capable of grasping the significance of the problem. Intellect is reasoning power as distinguished from feeling; it is often used in a general sense to characterize high mental ability: to appeal to the intellect, rather than the emotions. Intelligence is ability to learn and to understand; it is also mental alertness or quickness of understanding: A dog has more intelligence than many other animals. 6. Mind, brain, brains may refer to mental capacity. Mind is the philosophical and general term for the center of mental activity, and is therefore used of intellectual powers: a brilliant mind. Brain is properly the physiological term for the organic structure that makes mental activity possible ( The brain is the center of the nervous system. ), but it is often applied, like mind, to intellectual capacity: a fertile brain. Brains is the anatomical word ( the brains of an animal used for food ), but, in popular usage, it is applied to intelligence (particularly of a shrewd, practical nature): To run a business takes brains.