As a scientist, I like the idea of taking down creationist students. But this definition of "theory" is bullshit. It's historically inaccurate because you'll find histories of science that refer to the Ptolemaic Theory of the solar system or the phlogiston theory in chemistry, both of which are not only not well-supported, but flat-out wrong. In the humanities, you have literary theory and music theory. A theory is any collection of ideas and facts on a given subject. They can be well established, like atomic theory, speculative, like string theory, outright false, like (just to be different), the tectogene theory in geology (look it up), or non-scientific, like music theory. A hypothesis is a kind of theory, but theories are not necessarily hypotheses, which is how most people use the term. Also that definition of "theory" is intellectually dishonest, since it seems to have been concocted for the express purpose of countering the "evolution is just a theory" nonsense. But you don't deal with fallacies by redefining terms to make them go away.