(1):

(n.) The substance which constitutes the essential part of the solid framework of plants, of ordinary wood, linen, paper, etc. It is also found to a slight extent in certain animals, as the tunicates. It is a carbohydrate, (C6H10O5)n, isomeric with starch, and is convertible into starches and sugars by the action of heat and acids. When pure, it is a white amorphous mass. See Starch, Granulose, Lignin.

(2):

(a.) Consisting of, or containing, cells.