fast·​ness | \ ˈfas(t)-nəs How to pronounce fastness (audio) \

Definition of fastness

1 : the quality or state of being fast: such as
a : the quality or state of being fixed
b : the quality or state of being swift
c : colorfast quality
d : resistance (as of an organism) to the action of a usually toxic substance
2a : a fortified or secure place
b : a remote and secluded place vacationed in their mountain fastness

Examples of fastness in a Sentence

the amazing fastness with which the boy took his shower had us wondering if he'd used any water the guerillas retreated to their network of hidden fastnesses deep within the mountains
Recent Examples on the Web Test for color fastness before stitching onto bedding and washing. Sonja Carmon, Better Homes & Gardens, 14 Apr. 2021 Given their advance into Labour’s working-class fastness, the Tories’ worst nightmare is not a Labour Party that returns to the old centre as defined by Tony Blair. The Economist, 13 Dec. 2019 The other tragedy occurred far from the public eye, in one of the last remote fastnesses of the world. Ipsita Chakravarty, Quartz India, 10 June 2019 Indeed, Lego can't reach its 2030 goal without solving ABS, a material that affords the company the attributes it so prizes: Durability, color fastness, strength, and clutch power, or how well two joined bricks stay together. Brian Barrett, WIRED, 11 Mar. 2018 These enabled India to detect, and destroy by air, Pakistani troops entrenched in mountain fastnesses. Tunku Varadarajan, WSJ, 5 July 2017 India kept the mostly Hindu rest of Jammu, the Vale itself and the desert-like fastness of Ladakh. The Economist, 20 July 2017 See More

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

First Known Use of fastness

before the 12th century, in the meaning defined at sense 1

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The first known use of fastness was before the 12th century

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Fast of Esther

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Cite this Entry

“Fastness.” Dictionary, Merriam-Webster, Accessed 13 Aug. 2022.

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fast·​ness | \ ˈfas(t)-nəs How to pronounce fastness (audio) \

Medical Definition of fastness

: resistance (as of an organism) to the action of a usually toxic substance streptomycin fastness developed by a strain of tubercule bacillus


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