Relative viscosity

Relative viscosity ($\eta _{r}$) (a synonym of "viscosity ratio") is the ratio of the viscosity of a solution ($\eta$) to the viscosity of the solvent used ($\eta _{s}$),

$\eta _{r}={\frac {\eta }{\eta _{s}}}$.

References

• IUPAC Compendium of Chemical Terminology