olemus
liik süsteemiarenduse mudeleid, põhineb arendusjärkude järjestikku läbimisel
Wiktionary:
a sequential software development process in which development is seen as flowing steadily downwards (like a waterfall) through the phases of requirements analysis, design, implementation, testing, integration, and maintenance

ülevaateid
https://www.techtarget.com/searchsoftwarequality/definition/waterfall-model
https://en.wikipedia.org/wiki/Waterfall_model
https://www.boardinfinity.com/blog/a-quick-guide-to-arrays-in-python/
https://business.adobe.com/blog/basics/waterfall
https://codecourse.sourceforge.net/materials/The-Waterfall-Lifecycle-Model.html