A testable explanation for an observed phenomenon. A clarification on what meaning of "theory" {nger} indicates would be good too. If {nger} actually means something closer to the casual use of "theory" to mean something more like "a guess", then perhaps {nger} would be suitable for "hypothesis", and it would be good to have a word for the scientific meaning of "theory". However, if {nger} means "theory" in the scientific sense, then a word for "hypothesis" would be useful.