FASTNESS Synonyms: 108 Similar and Opposite Words

fastness

noun

ˈfas(t)-nəs

Definition of fastness

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

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

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

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.

Recent Examples of fastness The redyed fabrics showed uniform color uptake and washing and rubbing fastness comparable to the reference fabric, according to the study. — Alexandra Harrell, Footwear News, 26 Aug. 2026 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

Recent Examples of Synonyms for fastness

Noun

Lennon is electric, but technically Stone is Antioch’s speed back.

— Mike McGraw, Chicago Tribune, 29 Aug. 2026
The rise lifted some components of the index into overbought territory, as measured by the relative strength index (RSI), a momentum indicator that tracks the speed and size of price changes.

— Tobias Burns, CNBC, 29 Aug. 2026

Definition of speed

Noun

In the centuries that followed, the Mission went from Mexican farmland to immigrant stronghold as waves of working-class European families moved into the neighborhood following the Gold Rush in the mid-1800s.

— Marissa J. Lang, NPR, 28 Aug. 2026
Residents of Pale, a Bosnian Serb stronghold just outside of Sarajevo, mourned Mladic.

— Jovana Gec, Los Angeles Times, 27 Aug. 2026

Definition of stronghold

Noun

But without independent oversight into such decisions, oversight that Syria has yet to establish, centralization could also revive the Assad-era practice of offering economic access as a reward for political loyalty.

— Jesse Marks, Foreign Affairs, 31 Aug. 2026
The Basij run a nationwide network of volunteers who maintain a presence in the streets, government offices and cultural centers, seeking to ensure loyalty and ideological purity for Iran’s theocracy.

— Lee Keath, Fortune, 29 Aug. 2026

Definition of loyalty

Noun

Essentially a form of computational fluid dynamics, the simulation divides the flow passages into a very large number of tiny regions and calculates things such as velocity, pressure, turbulence, and temperature throughout the component.

— Christopher McFadden, Interesting Engineering, 29 Aug. 2026
The curves ahead are posted at a third of my current speed, but the big Brembos scrub off velocity easily, and the Slingshot rails through corner after corner.

— William Roberson, Forbes.com, 29 Aug. 2026

Definition of velocity

Noun

The terrain is a natural fortress, and bombing is of limited effectiveness.

— Danielle Parker, CBS News, 28 Aug. 2026
There is a micronation on a fortress at sea off the coast of Great Britain, and the British government once considered blowing it up.

— Encyclopedia Britannica, Encyclopedia Britannica, 27 Aug. 2026

Definition of fortress

Noun

But when al-Baghdadi announced in April 2013 that the Nusra Front would be folded into the Islamic State group, al-Sharaa refused and pledged allegiance to al-Qaida’s Ayman al-Zawahiri instead.

— Jason M. Blazakis, The Conversation, 27 Aug. 2026
Many New Yorkers who remained behind British lines during the war were not supporters of the Revolution, but in naming their son after George Washington, the Irvings declared their allegiance.

— Eric Lach, New Yorker, 26 Aug. 2026

Definition of allegiance

Noun

The area was incredibly special to Chamberlain, who first came out East to stay with Larry Rivers in Southampton, long before the town was a bastion of Sant Ambroeus and Brandy Melville.

— Nate Freeman, Vanity Fair, 21 Aug. 2026
He was tracked down in the town of Jesús María, a bastion of Los Chapitos on the outskirts of Culiacán, where another of El Chapo’s sons, Ovidio Guzmán López, was arrested after a firefight in 2023.

— Senior Editor, Los Angeles Times, 21 Aug. 2026

Definition of bastion

Noun

Our nurses play an essential role in caring for others with compassion and dedication, and this loss is being felt across our entire community.

— ABC News, ABC News, 31 Aug. 2026
Rogers’ heartfelt dedication touched on each of those points, remembering Parton for her charitable spirit and immense talent.

— Chris Parton, USA Today, 30 Aug. 2026

Definition of dedication

Browse Nearby Words

fasting

fastness

fasts

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Style

“Fastness.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/fastness. Accessed 1 Sep. 2026.

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Synonyms of fastness

noun

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