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noun

viscosity

vis-KOSS-i-tee

Viscosity (noun) means How thick a liquid is and how strongly it resists flowing; honey has a high viscosity, water a low one. Example: “Cold weather raises the viscosity of the oil, so the engine turns over slowly.”

noun
1
How thick a liquid is and how strongly it resists flowing; honey has a high viscosity, water a low one.
"Cold weather raises the viscosity of the oil, so the engine turns over slowly."
"Stir until the sauce reaches the viscosity of single cream."
2
technical In physics, a measurable property of a fluid equal to the ratio of shear stress to the rate of shear, expressed in units such as the pascal second or the poise.
"The dynamic viscosity of water at 20 °C is about one millipascal second."

How to Use Viscosity

Learner’s notes

In plain EnglishHow thick and slow-flowing a liquid is.

When to use it

Everyday in cooking and car maintenance, precise in engineering and physics, where dynamic and kinematic viscosity are distinguished.

Memory tip

The adjective is viscous (thick and sticky), not vicious — the two are often mistyped for each other.

Trace the full origin ↓
Easily confused with
density viscidity
Common pairings
high viscosity low viscosity oil viscosity viscosity index viscosity of blood
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Test yourself on “viscosity” A quick quiz — meaning, synonyms & usage

Fill the Gap

Can you complete this real example?

Cold weather raises the _____ of the oil, so the engine turns over slowly.

Etymology

From Latin viscosus "sticky", from viscum, the sticky birdlime made from mistletoe berries.

Origin: Latin

thickness stickiness consistency gloopiness internal friction

Antonyms

fluidity runniness

Related Words

Rhymes for viscosity

See all rhymes for viscosity →

Frequently Asked Questions

What is the difference between viscosity and density?

Density is how much mass a substance packs into a given volume; viscosity is how much it resists flowing. Motor oil is less dense than water but far more viscous, which is why it floats yet pours slowly.

Does viscosity change with temperature?

Yes, and strongly. Liquids get thinner as they warm and thicker as they cool, which is why cooking oil runs freely in a hot pan and honey stiffens in the fridge. Gases behave the opposite way, becoming slightly more viscous when heated.

What does 10W-40 mean on an oil bottle?

It is a viscosity grade. The number before the W describes how the oil flows in winter cold, and the second number how thick it stays at engine operating temperature.

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Definitions: FreeDict original editorial · etymology from FreeDict original editorial