[crazygringo]

> And in the dictionaries I've looked in, there are many usage senses of the word illegal that do cover things that are not criminal.

That wasn't the question under discussion -- my comment already had an example of that, of driving over the speed limit.

The question is whether breaking a contract falls under the term "illegal". And again, you're using logic to argue this, when it's simply a question of definition. It's not whether it should fall under the term "illegal", it's whether lawyers and lawmakers and other educated folks define the term that way.

And it doesn't seem like they do. It seems that someone is not acting "illegally" when they break a contract. They can be sued, the contract can be binding, but the word we use for the behavior is "breaching" or "violating", not "illegal".