1. Reactions involving the oxidation of organic substrates to provide chemically available energy (e.g. ATP) and to generate metabolic intermediates.
  2. Generally, the process of breakdown of complex molecules into simpler ones, often providing biologically available energy.
See also: anabolism
PAC, 1993, 65, 2003 (Glossary for chemists of terms used in toxicology (IUPAC Recommendations 1993)) on page 2013
PAC, 1992, 64, 143 (Glossary for chemists of terms used in biotechnology (IUPAC Recommendations 1992)) on page 149