Medical Definition of hyperviscosity
: excessive viscosity or thickness (as of the blood) As erythrocytosis due to arterial desaturation develops … symptoms of hyperviscosity (visual disturbances, fatigue, headache, dizziness, and paresthesias) may appear.—M. Elizabeth Brickner et al., The New England Journal of Medicine, 3 Feb. 2000
Seen and Heard
What made you want to look up hyperviscosity? Please tell us where you read or heard it (including the quote, if possible).