(1) The process involving a series of degradative chemical reactions that break down complex molecules into smaller units, usually releasing energy in the process.
(2) A destructive type of metabolism.
For instance, large molecules such as polysaccharides, nucleic acids and proteins are broken down into smaller units such as monosaccharides, nucleotides and amino acids, respectively.
Word origin: from Greek καταβολή (katabole), “‘throwing down’”), from κατά (kata), “‘down’”) + βάλλειν (ballein), “‘to throw’”).
See also: metabolism.