Newtonian fluids are fluids that continue to flow regardless of forces acting on them. Water is a Newtonian fluid. Non-Newtonian fluids act counter to what we might expect.
Etymology: dilatant is related to "dilate" (Latin); it refers to an increase in volume when the substance changes shape.
Dilatants are also called shear thickening materials. Shear thinning materials (materials whose viscosity decrease with rate of shear) include pseudoplastics and thixotropics.
Dilatants have been used in automobile traction control systems,and are being researched for use in body armor. That sounds a bit like the personal shields in Dune, which could only be breached by slow motions!
But this is supposed to be a food-themed post....
Ketchup is a pseudoplastic: it will stick inside the bottle, but when sufficiently shaken it will suddenly begin to flow freely. Yet once it's out of the bottle and no longer being shaken, it will stay in place (more or less) on your cheeseburger. It's science!
Oobleck is a dilatant. To make oobleck, mix 1 part water with roughly 2 parts cornstarch. The substance reacts much like a solid surface when struck, but like a liquid when touched. There are numerous online videos demonstrating the bizarre properties of oobleck, and it's a fun kitchen experiment. If you watch The Big Bang Theory, you might have seen oobleck on a speaker cone being turned into dancing blobs and spikes by the sound waves.