According to Stanford University, the 5 stages of design thinking are: empathy, definition, conception, prototype, and testing.
Empathy is working to understand the end user’s needs (the “problem statement”);
Definition is the elevator pitch of what problem you intend to solve and how;
Conception (or, ideation) is creative brainstorming (“ideate”) to find the best solution through product design;
Prototyping is creating the most basic version of your product;
Testing is turning that minimum viable product into a fully functional, QA tested, launch-ready item.