I've always thought the best definition of a warbow is a bow that can propel a genuine medieval battle arrow a reasonable distance, with enough force to penetrate or do significant damage to an armoured opponent.
If in doubt, make up a 1/2" poplar arrow, with a hand forged bodkin and 7" feathers, bound with silk or linen and see how your bow deals with it. If it flops away from the bow with no real purpose, the bow probably isn't a warbow. If the arrow flies off with serious force and you have to trudge through the mud for 200-300 yards to get it back, before swearing at the missing bodkin and half a feather pinned to a branch, you've got yourself a warbow!!
As Del said, any real definition or set of boundaries is daft, as although some discovered warbows can all fit into a certain bracket, none of them look like medieval drawings. Also we've found no warbows made of anything other than yew so design aspects are pretty irrelevant when you consider that an ash bow made to the 5/8 rule will suck as a warbow and yet ash was listed as true warbow wood by Ascham.