1
as in speed
a high rate of movement or performance
the amazing fastness with which the boy took his shower had us wondering if he'd used any water
Synonyms & Similar Words
Relevance
Antonyms & Near Antonyms
2
as in stronghold
a structure or place from which one can resist attack
the guerillas retreated to their network of hidden fastnesses deep within the mountains
Synonyms & Similar Words
3
as in loyalty
adherence to something to which one is bound by a pledge or duty
his uncompromising fastness to the cause of freedom was beyond question
Synonyms & Similar Words
Antonyms & Near Antonyms
Example Sentences
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Recent Examples of fastness
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, 20 Jan. 2026
Li said the color builds the familiar ring-dye, white-core look designers expect, then fades predictably in laundry while maintaining high light fastness (Grade 4–5) and strong anti-yellowing.
—Angela Velasquez, Sourcing Journal, 11 Nov. 2025
Like the pressing, the hard work mentality and fastness of transition for example.
—Andy Jones, New York Times, 29 May 2025
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
Yelena Moroz Alpert, Architectural Digest, 20 Jan. 2026
Li said the color builds the familiar ring-dye, white-core look designers expect, then fades predictably in laundry while maintaining high light fastness (Grade 4–5) and strong anti-yellowing.
—Angela Velasquez, Sourcing Journal, 11 Nov. 2025
Like the pressing, the hard work mentality and fastness of transition for example.
—Andy Jones, New York Times, 29 May 2025
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
Recent Examples of Synonyms for fastness
Noun
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Engineers from both organizations will examine how such reactors could support the high energy demand of container ships traveling long ocean routes at high speeds.—
Sujita Sinha,
Interesting Engineering,
9 Mar. 2026
-
Frithsmith got in some speed training.—
Eric Sondheimer,
Los Angeles Times,
9 Mar. 2026
Noun
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Smith prevailed in the primary again in 2022 and easily won a second term in this Republican stronghold, where Democrats haven’t put up a serious general election fight in recent years.—
USA Today,
USA Today,
8 Mar. 2026
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In response, Israel has ordered some 300,000 residents of Hezbollah's stronghold in Beirut to flee, taking out building after building.—
CBS News,
CBS News,
8 Mar. 2026
Noun
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The specialized formulas account for a very small part of Abbott’s revenue, though attorneys for parents suing the company say the formulas help Abbott build brand loyalty and secure hospital contracts.—
Lisa Schencker,
Chicago Tribune,
4 Mar. 2026
-
Feldman noted that Target continues to improve fulfillment and boost loyalty through its Target Circle.—
Lisa Kailai Han,
CNBC,
4 Mar. 2026
Noun
-
What are the relative velocities between them?—
Big Think,
Big Think,
3 Mar. 2026
-
Kairos' debut flight in March 2024 ended just five seconds after liftoff when the rocket's flight termination system detected lower-than-expected velocity and thrust.—
Mike Wall,
Space.com,
3 Mar. 2026
Noun
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Days are filled with swimming, snorkeling, birdwatching along the Florida Great Birding and Wildlife Trail, and exploring Fort Pickens, a 19th-century coastal fortress with panoramic views of the Gulf and bay.—
Carrie Honaker,
Travel + Leisure,
5 Mar. 2026
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Channel the Secret Garden storyline by adding the Peacock Alley Chloe percale set to your bedding fortress.—
Yelena Moroz Alpert,
Architectural Digest,
4 Mar. 2026
Noun
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The group reflects a place where boundaries, identities, and allegiances are always in flux.—
Carolina A. Miranda,
The Atlantic,
5 Mar. 2026
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At times the phrase is used to support the notion of America as a Christian nation or as one that owes its allegiance specifically to the Christian God.—
Peter Smith,
Los Angeles Times,
5 Mar. 2026
Noun
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Since its inception 35 years ago, Sony Pictures Classics — under the uncommonly consistent stewardship of co-chiefs Michael Barker and Tom Bernard — has been a bastion of socially minded cinema on the global stage.—
Karen Kramer,
Variety,
27 Feb. 2026
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For many decades, Memorial Day was seen as the bastion upon which our white wardrobe pieces were held back in the closet.—
Kaitlyn Yarborough,
Southern Living,
21 Feb. 2026
Noun
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The developer bumped up its open space dedication at the site to 132 acres late last week.—
John Aguilar,
Denver Post,
9 Mar. 2026
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The marathon is often the culmination of years of mentorship and dedication.—
Michelle Edgar,
Daily News,
8 Mar. 2026
Cite this Entry
“Fastness.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/fastness. Accessed 11 Mar. 2026.
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