What is the word theory used in science textbooks

Theory in the science textbooks is the statements of the scientist that are supported by many facts and that feature the nature.

Explanation:

The word theory used in science book and other places may have different meanings.

The casual day to day use of theory may suggest it as assumptions or anything like that but in the textbook it is called hypothesis not theory.

Theories are only the proven fact that supports the nature and are realistic.