Oobleck – a cornflour and water mixture named after a substance in a Dr Seuss book – initially behaves like a liquid or a jelly. However, when you squeeze it in your hand, it behaves like a solid for a short time. It becomes more viscous when agitated or compressed and belongs to a subset of non-Newtonian fluids called dilatants. When a force is applied to a dilatant, its viscosity increases.
Oobleck is a mixture of cornstarch and water. Oobleck is a non-Newtonian fluid. When some force is applied it reacts like a solid for a short moment before it returns to its liquid behaviour.