Illustrated Glossary of Organic Chemistry

Endergonic: A process such as a chemical reaction in which the Gibbs free energy (G) of the products is greater than the Gibbs free energy of the reactants (i.e., ΔG > 0). Work (energy) must be absorbed from the surroundings for the reaction to proceed. Such processes are not thermodynamically spontaneous (i.e., K_eq < 0).

Energy profile for a concerted endergonic reaction.