- a fluid that exhibits frictionless flow, very high heat conductivity, and other unusual physical properties, helium below 2.186 K being the only known example.
- of or relating to a superfluid.
- a fluid in a state characterized by a very low viscosity, high thermal conductivity, high capillarity, etc. The only known example is that of liquid helium at temperatures close to absolute zero
- being or relating to a superfluid
