su·per·crit·i·cal / ˌsoōpərˈkritikəl/ • adj. Physics above a critical threshold, in particular: ∎ (in nuclear physics) containing or involving more than the critical mass. ∎ (of a flow of fluid) faster than the speed at which waves travel in the fluid. ∎ denoting an airfoil or aircraft wing designed to tolerate shock-wave formation at transonic speeds. ∎ of, relating to, or denoting a fluid at a temperature and pressure greater than its critical temperature and pressure.