viscosity index


: an arbitrary number assigned as a measure of the constancy of the viscosity of a lubricating oil with change of temperature with higher numbers indicating viscosities that change little with temperature

Examples of viscosity index in a Sentence

Recent Examples on the Web An oil’s resistance to thinning in hotter temperatures is called the viscosity index. Paul Weissler, Popular Mechanics, 31 Aug. 2020 Resistance to thinning with increasing temperature is called viscosity index. Paul Weissler, Popular Mechanics, 14 Feb. 2019

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'viscosity index.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1929, in the meaning defined above

Time Traveler
The first known use of viscosity index was in 1929

Dictionary Entries Near viscosity index

Cite this Entry

“Viscosity index.” Dictionary, Merriam-Webster, Accessed 28 May. 2024.

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