viscosity

noun vis·cos·i·ty \ vi-ˈskä-sə-tē \

Updated on: 3 Apr 2018

Definition of viscosity

plural viscosities

1 : the quality or state of being viscous : a sticky or glutinous consistency

2 a 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

See viscosity defined for kids

Examples of viscosity in a Sentence

conducted an experiment to determine the viscosity of motor oil

Recent Examples of viscosity from the Web

Not to mention, when that time of the month rolls around, the oil beneath your skin changes consistency from an olive oil type of thickness to a honey-like viscosity.

— carly cardellino, Cosmopolitan, "15 Acne-Causing Behaviors You Didn’t Even Know You Were Doing," 10 Jan. 2017
Break it in two at room temperature and its various layers will stretch and ooze at different delicious viscosities.

— steve hendrix, Washington Post, "‘Not built for this’: What fails in the extreme cold? Just about everything.," 4 Jan. 2018
Today's engines prefer high-viscosity oils — such as 5W-20 — that flow through your engine more smoothly in cold temperatures.

— dwight adams, Indianapolis Star, "Here's what to do when a car won't start in cold weather," 2 Jan. 2018
Solution: The Car Care Council recommends switching to low-viscosity oil in the winter.

— david muller, Car and Driver, "How Severe Cold Affects Your Car (and What to Do about It)," 5 Jan. 2018
This viscosity paired with the speed at which the magma rises determines the volcano’s explosivity, says Andrews: The thicker and quicker the lava, the more explosive the blast.

— maya wei-haas, Smithsonian, "Geology Makes the Mayon Volcano Visually Spectacular—And Dangerously Explosive," 19 Jan. 2018
All leading brands have one for service level SL, available in several viscosities.

— timothy dahl, Popular Mechanics, "How To Pick The Right Motor Oil For Your Car," 18 Jan. 2018
Theoretical physicists Dam Thanh Son and Andrei Starinets, for example, collaborated on an idea that used black hole math to predict the viscosity of an ultrahot gas, or plasma, that forms in certain particle collider experiments.

— steve nadis, Discover Magazine, "Black Holes and Revelations," 6 Oct. 2017
Softness and viscosity are common metrics for comparing solid and fluid materials, respectively.

— alexis noel and david hu, Smithsonian, "Inside Every Frog’s Mouth Is a Sticky, Grabby Bullet," 1 Feb. 2017

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.

Origin and Etymology of viscosity

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

NEW! Time Traveler

First Known Use: 14th century

See Words from the same year

viscosity Synonyms

Synonyms

consistence, consistency, density, thickness, viscidity;

Related Words

compactness, firmness, solidity;

ropiness, stickiness;

Other Chemical Engineering Terms

alkali, cation, decant, hygroscopic, isotope, oxidize, slurry, solute, viscous

Medical Dictionary

viscosity

noun vis·cos·i·ty \ vis-ˈkäs-ət-ē \

medical Definition of viscosity

plural viscosities

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