vis·​cos·​i·​ty | \ vi-ˈskä-sə-tē How to pronounce viscosity (audio) \
plural viscosities

Definition of viscosity

1 : the quality or state of being viscous : a sticky or glutinous consistency
2a technical : the property of resistance to flow in any material with fluid properties … water has a small but measurable viscosity, or "stickiness," which results from the weak mutual attraction of water molecules.— Hans Christian von Baeyer
b : the mathematical ratio of the tangential frictional force per unit area to the velocity gradient perpendicular to the direction of flow of a liquid

called also coefficient of viscosity

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Examples of viscosity in a Sentence

conducted an experiment to determine the viscosity of motor oil
Recent Examples on the Web Their high sugar content just gives them a creamlike viscosity. Mike Sutter,, "9 things we learned at the 2020 San Antonio Cocktail Conference," 22 Jan. 2020 Lip fillers like Juvéderm and Restylane inject a high viscosity filler into the lip to add volume. Harper's BAZAAR, "What is a Botox Lip Flip? Experts Weigh In.," 26 Dec. 2019 Her approach: Use a medium- to high-viscosity hyaluronic acid filler (like Restylane Refyne, Restylane Defyne, or Versa) to build the height of the top and bottom lip to showcase more of their pinkness. Jolene Edgar, Allure, "The Innovative New Ways Surgeons Are Using Injectables to Sculpt the Human Face," 15 Jan. 2020 Some volcanoes—think Hawaii’s Kilauea—erupt runny lavas with lower viscosity. Jennifer Leman, Popular Mechanics, "Everything You Ever Wanted To Know About Volcano Eruptions," 18 Nov. 2019 Not quite as watery, a little more viscosity to it. Trevor Fraser,, "Retro speakeasy Park Social keeps it simple with Bourbon Amaretto Sour," 25 Sep. 2019 When Katz and Pavlovic tried to extend their process to a toy version of the Navier-Stokes equations, the fluid’s viscosity snuffed out this thinned-out energy and no blowup occurred. Quanta Magazine, "A Fluid New Path in Grand Math Challenge," 24 Feb. 2014 The dealer says to change the oil (zero viscosity) every 10,000 miles. Bob Weber,, "Motormouth: Don’t worry about tires that have sat in a warehouse," 15 Nov. 2019 The chemistry used for the battery is zinc iodide, which was chosen for a combination of high energy density (in theory, up to half that of current lithium-ion batteries), neutral pH, and low viscosity (important for a hydraulic fluid). John Timmer, Ars Technica, "Researchers make a robotic fish with a battery for blood," 19 June 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'viscosity.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of viscosity

14th century, in the meaning defined at sense 1

History and Etymology for viscosity

Middle English viscosite, from Anglo-French viscosité, from Medieval Latin viscositat-, viscositas, from Late Latin viscosus viscous

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Time Traveler for viscosity

Time Traveler

The first known use of viscosity was in the 14th century

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Statistics for viscosity

Last Updated

5 Feb 2020

Cite this Entry

“Viscosity.” Dictionary, Merriam-Webster, Accessed 28 Feb. 2020.

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More Definitions for viscosity


vis·​cos·​i·​ty | \ vis-ˈkäs-ət-ē How to pronounce viscosity (audio) \
plural viscosities

Medical Definition of viscosity

1 : the quality of being viscous especially : the property of resistance to flow in a fluid or semifluid
2 : the ratio of the tangential frictional force per unit area to the velocity gradient perpendicular to the direction of flow of a liquid

called also coefficient of viscosity

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