We define polynomial time computable operator. Our definition generalizes Cook's definition to arbitrary function inputs. Polynomial classes are defined in terms of these operators; the properties of these classes are investigated. Honest polynomial classes are generated by running time. They possess a modified Ritchie-Cobham property. A polynomial class is a complexity class if it is honest. Starting from the observation that many results about subrecursive classes hold for all reducibility relations (e.g. primitive recursive in, elementary recursive in), which were studied so far, we define abstract subrecursive reducibility relation. Many results hold for all abstract subrecursive reducibilities.