A structured approach to software development and project management characterised by clearly delineated phases of work based around designing a solution, building the solution, testing the solution and then releasing the solution. These stages happen in order, and as such, there is little flexibility to change the end product after the design phase is complete without incurring additional cost.
Typically viewed as the opposite of agile techniques and an “old fashioned” way of doing things by anyone with artisan coffee in hand. Waterfall hasn’t helped itself by being behind a number of enormous over spends on big change programmes.
Luckily, agile and especially poor deployment of agile (or fragile development) is increasingly becoming just as much of a money suck for firms.