Data lake, is commonly used for describing a large-scale tool where multiple data sources from different types of systems are fed in and parsed in pre-defined methods.
However, it is also quite common to see where incompetent peeps use when they do not understand a dime about data or data-science. Since it is not publicly well studied or understood area, some peeps use this 'term' to fool non-technical executives to extend their own projects.
A: "We will build a massive data lake, analyze everything from all the sensors with AI on the fly, orchestrate all the processes and automate everything and everyone's tasks"
B: Oh, that's nice. So you can hand in your resignation next year after delivering this project.
A: Ups. That was a nice outcome.