What is any of a group of sugars of the formula C5H10O5, as arabinose; -- so called from the five carbon atoms in the molecule. They are not fermented by yeast called?

pentose — Any of a group of sugars of the formula C5H10O5, as arabinose; -- so called from the five carbon atoms in the molecule. They are not fermented by yeast. (Webster's 1913.)

Sources