fastness
noun
fast·ness
ˈfas(t)-nəs 
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
2
a
: 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
Like the pressing, the hard work mentality and fastness of transition for example.
—
Andy Jones, New York Times, 29 May 2025
Editors and contributors compare dozens of sets and look for qualities such as softness, durability, breathability, color fastness, and how well the linens launder and withstand wear.
—Yelena Moroz Alpert, Architectural Digest, 16 May 2025
The system ensures good wet-rubbing and dry-rubbing fastness and softness on all kinds of fabrics.
—Angela Velasquez, Sourcing Journal, 30 Dec. 2024
The system ensures good wet-rubbing and dry-rubbing fastness and softness on all kinds of fabrics.
—Angela Velasquez, Sourcing Journal, 30 Dec. 2024
Tat-Fung’s Downtown collection of blue, black and gray fabrics outperform conventional denim in color fastness, according to Tim Huesemann, the mill’s sales director.
—Angela Velasquez, Sourcing Journal, 22 Oct. 2024
This advancement enables dyeing with Basic dyes, promising enhanced dye uptake and superior wash fastness compared to traditional Reactive dyes.
—Sj Studio, Sourcing Journal, 13 Sep. 2024
The Neutral Ground had cowboys (or Cow Boys), Indians, cavalry attacks and rescues, and secret woodland fastnesses known only to the canniest frontiersman.
—Ian Frazier, The New Yorker, 15 July 2024
The technology uses specific formaldehyde-free agents to enhance the dyeing process of raw garments, resulting in a bright and deep indigo color, improving wash and rubbing fastness, and increasing lightfastness and levelness.
—Andrea Onate, WWD, 12 June 2024
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Andy Jones, New York Times, 29 May 2025
Editors and contributors compare dozens of sets and look for qualities such as softness, durability, breathability, color fastness, and how well the linens launder and withstand wear.
—Yelena Moroz Alpert, Architectural Digest, 16 May 2025
The system ensures good wet-rubbing and dry-rubbing fastness and softness on all kinds of fabrics.
—Angela Velasquez, Sourcing Journal, 30 Dec. 2024
The system ensures good wet-rubbing and dry-rubbing fastness and softness on all kinds of fabrics.
—Angela Velasquez, Sourcing Journal, 30 Dec. 2024
Tat-Fung’s Downtown collection of blue, black and gray fabrics outperform conventional denim in color fastness, according to Tim Huesemann, the mill’s sales director.
—Angela Velasquez, Sourcing Journal, 22 Oct. 2024
This advancement enables dyeing with Basic dyes, promising enhanced dye uptake and superior wash fastness compared to traditional Reactive dyes.
—Sj Studio, Sourcing Journal, 13 Sep. 2024
The Neutral Ground had cowboys (or Cow Boys), Indians, cavalry attacks and rescues, and secret woodland fastnesses known only to the canniest frontiersman.
—Ian Frazier, The New Yorker, 15 July 2024
The technology uses specific formaldehyde-free agents to enhance the dyeing process of raw garments, resulting in a bright and deep indigo color, improving wash and rubbing fastness, and increasing lightfastness and levelness.
—Andrea Onate, WWD, 12 June 2024
Cite this Entry
“Fastness.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fastness. Accessed 21 Jul. 2025.
Copy CitationKids Definition
fastness
noun
fast·ness
ˈfas(t)-nəs
1
: the quality or state of being fast
2
: a fortified or secure place
Medical Definition
fastness
noun
fast·ness
ˈfas(t)-nəs
: resistance (as of an organism) to the action of a usually toxic substance
streptomycin fastness developed by a strain of tubercule bacillus
Love words? Need even more definitions?
Merriam-Webster unabridged
Share