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• hard-and-fast
  hard-and-fast

  adjective

  strongly binding; not to be set aside or violated.
• hard and fast
  hard and fast

  adjective

  (hard-and-fast when prenominal) (esp of rules) invariable or strict

hard-and-fast

American  

[hahrd-n-fast, -fahst] / ˈhɑrd nˈfæst, -ˈfɑst /

adjective

1. strongly binding; not to be set aside or violated.

   hard-and-fast rules.

   Synonyms:

   unambiguous, rigorous, inviolable, inflexible, precise, fixed

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hard and fast British  

adjective

1. (hard-and-fast when prenominal) (esp of rules) invariable or strict

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hard and fast Idioms  

1. Defined, fixed, invariable, as in We have hard and fast rules for this procedure. This term originally was applied to a vessel that has come out of water, either by running aground or being put in dry dock, and is therefore unable to move. By the mid-1800s it was being used figuratively.

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Other Word Forms

• hard-and-fastness
  noun

Etymology

Origin of hard-and-fast

First recorded in 1865–70

Example Sentences

See Examples For:

hard-and-fast hard and fast

"But a blanket hard-and-fast rule isn't helpful, because it doesn't really allow for the intricacies and the individualisation of what's really going on."

From BBC ● Sep. 17, 2026

That’s not because the travel industry has a hard-and-fast rule about when to buy flights, but because the loosely understood best practice of a one-to-three-month advance window for nonholiday travel hasn’t arrived yet.

From Slate ● May 12, 2026

Also, California has few hard-and-fast rules on residency.

From The Wall Street Journal ● Jan. 25, 2026

I’m not necessarily sold on hard-and-fast rules when it comes to age; it also depends on your risk tolerance, expected longevity and how long you intend to work.

From MarketWatch ● Dec. 11, 2025

Unfortunately, there’s no hard-and-fast rule that tells you how to form the plural of every word that ends in o.

From "Woe Is I" by Patricia T. O'Conner

There’s no hard and fast rule for how quickly, or not, airlines have to act if they are going to cancel a mistake fare.

From The Wall Street Journal ● Apr. 22, 2026

While there is no hard and fast definition of what constitutes a TACO, several Wall Street professionals who spoke with MarketWatch for this story agreed with our list of nine specific events.

From MarketWatch ● Apr. 8, 2026

You warned that what we believed to be hard and fast rules protecting the free press were really just soft norms.

From Slate ● Feb. 24, 2026

Vigorous exercise makes you breathe hard and fast.

From BBC ● Jan. 20, 2026

His investors’ requests for their money back came in hard and fast.

From "The Big Short" by Michael Lewis