viscosity index


Definition of 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

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Resistance to thinning with increasing temperature is called viscosity index. Paul Weissler, Popular Mechanics, "How to Pick the Right Motor Oil for Your Car," 14 Feb. 2019 Resistance to thinning with increasing temperature is called viscosity index. Timothy Dahl, Popular Mechanics, "How To Pick The Right Motor Oil For Your Car," 18 Jan. 2018

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

First Known Use of viscosity index

1929, in the meaning defined above

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Last Updated

20 Mar 2019

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The first known use of viscosity index was in 1929

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