In English grammar, an abstract noun is a noun or noun phrase that names an idea, event, quality, or conceptâfor example, courage, freedom, progress, love, patience, excellence, and friendship. An abstract noun names something that can't be physically touched. Contrast with concrete noun.
The adult human brain weighs on average about 1.2â1.4 kg (2.6â3.1 lb), or about 2% of total body weight, with a volume of around 1260 cm3 in men and 1130 cm3 in women, although there is substantial individual variation.
Physical Facts About the Brain. The adult human brain weights about 3 pounds and the cerebrum accounts for about 85% of the brain. The brain is composed of 40% gray and 60% white matter. The gray matter is made up of about 100 billion neurons that gather and transmit signals while the white matter is made of dendrites and axons that the neurons use to transmit signals. The brain is composted of about 75% water and is the fattiest organ in the body, consisting of a minimum of 60% fat. Humans have the largest brain to body ratio of any animal, and the blood vessels in the brain, if stretched end-to-end, would be about 100,000 miles long.