Origin: Anc Greek θεωρία/theoria (=the way that the things looked at, conception, viewing) > θεωρώ/theoro> θέα/thea(=view) + ορώ (look at, consider).
A set of statements or conceptions devised to make a framework for describing or explaining a phenomen. A theory is a based upon a hypothesis and backed by evidence.
Runon derivatives :
theory is opposed of action or practice