The waterfall development model is a software development model that has been widely used since the 1970s. It is a linear and sequential approach to software development, where each phase of the project must be completed before moving on to the next one. However, there are other synonyms for this development model that can assist software developers. Some key alternatives include the sequential development model, the linear sequential model, the traditional model, and the software development life cycle model. While these approaches share some similarities with the waterfall model, they all differ in their respective goals, technology, and organizational structure, which is why developers must consider each one when choosing the best development model for their project.