Osmotic pressure Osmotic pressure is defined as: > The pressure that would have to be applied to a pure solvent to prevent it from passing into a given solution by osmosis. And yet water moves from low osmotic pressure to high osmotic pressure. Shouldn't high osmotic pressure prevent osmosis? It would be really helpful is this definition were explained.

The definition in your first paragraph doesn't match your understanding in the second. If osmotic pressure is high in "A" relative to "B", you would _have to apply a physical pressure to "A" to prevent solvent moving from B to A_. If there is no such pressure applied, then solvent does move from B to A. The osmotic pressure and physical pressure are separate and opposite forces.

I prefer to think of osmotic pressure as sort of a "vacuum" that "pulls" solvent towards it (of course it isn't really a vacuum so don't take this analogy too far...). The definition still works given this form of thinking: you'd have to apply as much external pressure to equal the "vacuum" in order to have no movement of solute.