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 ($\eta _{s}$),

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

References

• IUPAC Compendium of Chemical Terminology