Final answer:
A reaction that yields a single product from two or more reactants is termed a composition or combination reaction, exemplified by the general equation A+B → AB.
Step-by-step explanation:
A reaction in which two or more substances react to produce a single product is known as a composition reaction, which can also be referred to as a combination or synthesis reaction. In essence, the combination of reactants yields a single, more complex product. The generic chemical equation for such a reaction is A+B → AB, signifying that substances A and B react to form substance AB. This reaction type differs from a decomposition reaction, where a single substance splits into two or more products.