that portion of food composed of carbohydrates which are completely or partly indigestible, such as cellulose or pectin; it may be in an insoluble or a soluble form. It provides bulk to the solid waste and stimulates peristalsis in the intestine. It is found especially in grains, fruits, and vegetables. There is some medical evidence which indicates that diets high in fiber reduce the risk of colon cancer and reduce cholesterol levels in the blood. It is also called dietary fiber, roughage, or bulk.
fibra = fibre (Vesalius, c. 1550); original meaning was a lobe, e.g., of lung, liver, or bowels examined for prophecies.
the nondigestible parts of the plants that we eat, such as cellulose, also known as roughage. Fibre is an essential part of our diet.