Viscosity rhymes with:
animosity, atrocity, curiosity, ferocity, generosity, monstrosity, religiosity, velocity, analyticity, animosity, atrocity, audacity, biodiversity, capacity, complexity, complicity, curiosity, density, diversity, domesticity, eccentricity, elasticity, electricity, falsity, felicity, ferocity, generosity, incapacity, intensity, laxity, monstrosity, necessity, obesity, opacity, overcapacity, paucity, perplexity, perversity, publicity, religiosity, simplicity, specificity, toxicity, university, velocity, voracity
Viscosity sounds like:
vacate, vacated, vaguest, vajda, vashti, vast, vasta, vaught, vegetate, vest, vesta, vested, vexed, vicissitude, visigoth, visit, visited, vist, vista, voest, voght, vogt, voiced, voight, voigt, vojta, vouched, vought, voyaged