My answer to What is Kinematic viscosity?
Answer by Arûn Râinâ:
The SI unit of kinematic viscosity is m/s. The cgs physical unit for kinematic viscosity is the stokes (St), named after George Gabriel Stokes. It is sometimes expressed in terms of centistokes (cSt). In U.S. usage, stoke is sometimes used as the singular form.The viscosity of ais a measure of its to gradual deformation by or For liquids, it corresponds to the informal concept of "thickness". For example, has a much higher viscosity than .Viscosity is a property arising from collisions between neighboring particles in a fluid that are moving at different . When the fluid is forced through a tube, the particles which compose the fluid generally move more quickly near the tube's axis and more slowly near its walls: therefore some , (such as a difference between the two ends of the tube), is needed to overcome the friction between particle layers to keep the fluid moving. For the same velocity pattern, the stress required is proportional to the fluid's viscosity.
A fluid that has no resistance to shear stress is known as an ideal or inviscid fluid. Zero viscosity is observed only atin . Otherwise, all fluids have positive viscosity, and are technically said to be viscous or viscid. In common parlance however, a liquid is said to be viscous if its viscosity is substantially greater than that of water; and may be described as mobile if the viscosity is noticeably less than water
The word "viscosity" is derived from the"viscum", meaning and also a viscous made from mistletoe berries