viscosity

noun

vis·​cos·​i·​ty vi-ˈskä-sə-tē 

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

Synonyms of viscosity

• consistency
• consistence
• thickness

Examples of viscosity in a Sentence

conducted an experiment to determine the viscosity of motor oil

Recent Examples on the Web

Not too sweet with a nice viscosity, this syrup was well-liked by our editors. —Melinda Salchert, Southern Living, 20 Dec. 2025

The low viscosity of the slush still allows the moon to bulge and compress in response to Saturn’s tides, and to remove the heat that would otherwise melt the ice and form an ocean. —New Atlas, 18 Dec. 2025

Higher viscosity adds resistance. —Aamir Khollam, Interesting Engineering, 26 Nov. 2025

Spicin’s Quality Control Chef Cianna Means monitors each batch’s viscosity, as well as sugar, salt and water levels to make sure microbes are held at bay. —Kansas City Star, 18 Nov. 2025

Word History

Etymology

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

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing viscosity

• coefficient of viscosity
• viscosity index

Rhymes for viscosity

• atrocity
• ferocity
• monstrosity
• pomposity
• porosity
• precocity
• schistosity
• velocity
• verbosity
• animosity
• curiosity
• generosity

Kids Definition

viscosity

noun

vis·​cos·​i·​ty vis-ˈkäs-ət-ē 

plural viscosities

: the quality or state of being viscous

especially : the characteristic of a fluid that resists flow

an oil of high viscosity

Medical Definition

viscosity

noun

vis·​cos·​i·​ty vis-ˈkäs-ət-ē 

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