The term "waterfall", like the terms "capitalism" and "meritocracy", was coined to criticize the (previously unnamed) concept that it defined. "Waterfall" was

The term "waterfall", like the terms "capitalism" and "meritocracy", was coined to criticize the (previously unnamed) concept that it defined. "Waterfall" was Royce's term for the way software projects ended up being organically managed by people who weren't putting much thought into optimizing their organization. While I definitely agree that the "waterfall" style of "define everything up front, and then do all the stuff that you defined" is absolutely braindead, the alternatives are unfortunately even more braindead.