Why is it called the general theory of relaticity and notthe general hypothesis of relativity?

The term "theory" in "general theory of relativity" indicates a well-substantiated framework that has been extensively tested and validated through experimentation and observation. In contrast, a "hypothesis" refers to a preliminary explanation that requires further investigation. Albert Einstein's general theory of relativity provides a comprehensive understanding of gravitation and spacetime, making it a robust scientific theory rather than a mere hypothesis.