macromolecule catabolic process GO:0009057 GO:0043285 The chemical reactions and pathways resulting in the breakdown of a macromolecule, any molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass. biological_process biopolymer catabolic process macromolecule breakdown macromolecule catabolism macromolecule degradation