Term: apo- https://doi.org/10.1351/goldbook.A00416 Definition: An unitalicized prefix, preceded by a locant, used to indicate that all of the molecule beyond the carbon atom corresponding to that locant has been replaced by hydrogen atoms. Source: White Book, 2nd ed., p. 230 (https://iupac.qmul.ac.uk/bibliog/white.html) Citation: 'apo-' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.A00416 License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.