The creation of a design for a product, including the generation of data to substantiate the warranty (whether implicit or explicit).
Note that this is distinct from “manufacturer” of an item: a manufacturer may, or may not, be the developer of the item. The developer typically bears a significant share of liability for the correctness of the design (possibly all of it, depending on the contractual and legal circumstances under which development occurred).
Note that there is no restriction here with respect to whether or not the design was created in response to a set of requirements, which would typically be applicable only to CRAD. Even in the commercial context there will often be a “spec sheet” or some pre-development sales guarantees for high-cost development projects.