[voidlogic]

IMHO if it doesn't have predictive power it cannot be a theory:

the·o·ry noun \ˈthē-ə-rē, ˈthir-ē\ : an idea or set of ideas that is intended to explain facts or events

[swombat]

Explanation and prediction are two different things.

Your definition doesn't even require explanation - it just requires intent to explain.

So for example, "the moon is made of cheese" is a theory according to the definition you just quoted. It's an idea that is intended to explain the composition of the moon.