What is the definition of coenzyme

Organic small molecules that bind loosely to enzyme proteins and are easily separated from the protein portion by dialysis.
Due to changes in the chemical composition of coenzymes in enzyme catalyzed reactions, coenzymes can be considered as a special substrate or "second substrate". This so-called second substrate can be utilized by many enzymes. For example, it is known that there are about seven hundred enzymes that can be catalyzed using the coenzyme NADH.
In cells, the coenzyme after reaction can be regenerated to maintain its intracellular concentration at a stable level. For example, NADPH can be regenerated through the pentose phosphate pathway and S-adenosylmethionine under the action of methionine adenosyltransferase. Due to the necessity of coenzyme regeneration for maintaining the stability of enzyme reaction systems, coenzyme regeneration systems have gained a large number of laboratory and industrial applications. Coenzymes cannot be called catalysts