A tensorial ordering parameter, obeying a linear relaxation equation, is introduced to describe the elastic shearing strain exhibited by a liquid at high frequencies. The coefficients in the relaxation‐rate equation and the shear modulus in the stress tensor are linked by the Onsager‐Casimir reciprocal relations with the result that the total rate of deformation is divided into elastic and viscous parts, in agreement with a hypothesis made by Frenkel to derive the viscoelastic stress relaxation equation of Maxwell. The hypersound wave velocity is computed from the thermal conductivity by an adaptation of a theory of Debye and from it the shear modulus and shear relaxation time are computed, effects of thermal relaxation being taken into account. In three nonassociated liquids, order‐of‐magnitude agreement is found with values calculated from a theory by Mooney.