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Simultaneous operation of two distinct catalytic cycles that jointly produce one product constitutes cocatalysis (dual or synergistic catalysis). Each catalyst activates a different substrate or a different elementary step; neither cycle alone is competent for the overall transformation under the same conditions. Photoredox/palladium cocatalysis for enantioselective allylic alkylation pairs a radical-generating photocatalyst with a chiral palladium π-allyl cycle ^[1]. Brønsted-acid promotion of rhodium-catalyzed asymmetric hydrogenation of N-unprotected indoles is a cocatalytic arrangement in which the acid and the metal complex share the catalytic workload ^[2]. Nickel/decatungstate cocatalysis for acylation of aryl halides and α-bromo acetates with aldehydes likewise assigns hydrogen-atom transfer and cross-coupling to two separate catalysts ^[3]. The term requires turnover of both species and a mechanistic interconnection (shared intermediate, sequential activation, or concerted dual activation). A ligand, solvent, or stoichiometric additive that is not regenerated is not a cocatalyst. Cocatalysis is therefore a systems-level description of how two catalytic manifolds are coupled, not a synonym for any single named reaction.