For each of us there are good words we haven't seen before. That's lucky, since life would be duller otherwise.

That's because it means exactly the same thing as "unorthodox" and almost everyone simply says that. Hence the discussion - you aren't alone.

When given the choice of a naming a variable notSomethingDescriptive or somethingElseDescriptive, I always choose the positive name, because it's easier to understand in logical expressions, and reduces double negation. It's better to describe what something is, instead of what it's not. So unOrthoDox is more negative (and more complex) than heteroDox, because it begins with the prefix "un".

You're right, but on the other hand, it's probably not best to use words that few are familiar with if you are trying to make yourself understood. On the gripping hand, a variable name is just a variable name and its true meaning doesn't really depend on its name at all, so okay, go for the burn. (especially if you're writing Java code)