lignin

noun

1. Botany. an organic substance that, with cellulose, forms the chief part of woody tissue.
2. Papermaking. impure matter found in wood pulp.

noun

1. a complex polymer occurring in certain plant cell walls making the plant rigid

n.1822, from Latin lignum “wood” (see ligni-) + chemical suffix -in (2).

1. A complex organic compound that binds to cellulose fibers and hardens and strengthens the cell walls of plants. Lignin is a polymer consisting of various aromatic alcohols, and is the chief noncarbohydrate constituent of wood.