Just to be clear: "theory" has a lot of different meanings, depending on the context. It can mean "hypothesis", but I can think of at least three other meanings, with example phrases: "Marxist theory"[1], "the theory of evolution"[2], "group theory"[3]...

As you're probably aware, this confusing patchwork of similar and overlapping yet distinct meanings is ripe for abuse: it's what allows people to get away with saying things like "evolution is just a theory".

[1] Here it means "the collective body of work of some school of thought".

[2] "A widely-accepted, well-tested scientific explanation for a phenomenon".

[3] "A subfield of mathematics; the set of definitions, theorems, and techniques related to a particular type of abstract object" (in this case, groups).

Yeah, the word "theory" is heavily overloaded and I wanted to keep it snappy so I just specified "general usage" and "in mathematics" to try and keep it on track. :)

I would correct that, for physics at least -- "theory" is just an explanation for something. "Law" is an experimental observation that holds true, but doesn't provide an explanation. E.g. Newton's laws describe macroscopic non-relativistic motion pretty well, but do not explain motion. The theory of relativity, on the other hand, explains the description of a bunch of physical phenomena, and also has lots of evidence behind it.