The concept of product development is a static thing. Product development always has the same definition. As the link below says, product development can be defined as
the process by which a company does one of two things: 1) creates an entirely new product that either adds to an existing product line or occupies an entirely new niche; 2) modifies or updates an existing product.
This definition does not change over time.
However, product development as a process is quite the opposite of static. The whole point of product development (as the quote above suggests) is to cause change. A firm must constantly be updating products to improve them or seeking to provide new products. If it does not, it will have a hard time competing in the market. This is clearly not something that is static.