In fluid mechanics (specifically rheology), a rheoscope is an instrument for detecting or measuring the viscosity of a fluid. In the study of blood flow, a rheoscope is used to observe and measure the deformation of blood cells subject to different levels of fluid shear stress.
References
Stein, Jess, ed. (1980). The Random House college dictionary. Random House. p. 1132. ISBN 0-394-43600-8.