unless

American  

[uhn-les, uhn-] / ʌnˈlɛs, ən- /

conjunction

1. except under the circumstances that.

   I'll be there at nine, unless the train is late.

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preposition

1. except; but; save.

   Nothing will come of it, unless disaster.

unless British  

/ ʌnˈlɛs /

conjunction

1. (subordinating) except under the circumstances that; except on the condition that

   they'll sell it unless he hears otherwise

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preposition

1. rare except

Etymology

Origin of unless

1400–50; late ME prepositional phrase on less (also o less(e) , earlier upon less ) on a lesser footing or condition (than); first used as a preposition and conjunction in the early 16th century; see on, less

Example Sentences

Assisted by his Team UAE colleague Isaac del Toro, Pogacar attacked with more than 25 miles to go, the kind of stunt you don’t pull unless you’re supremely confident.

From The Wall Street Journal • Jul. 10, 2026

“I don’t see any long-term reason why they would not do so, unless of course the entire AI cycle goes bust,” he said.

From MarketWatch • Jul. 8, 2026

England will not face one of the top 10 unless they come up against Argentina in the potential semi-final.

From BBC • Jul. 8, 2026

Secretary of State Marco Rubio notified Congress of the long-expected move, which will be effective in 45 days unless lawmakers take the unlikely step of blocking it.

From Barron's • Jul. 8, 2026

True, her salary was generous, but Lady Constance rarely thought to pay it unless asked.

From "The Interrupted Tale" by Maryrose Wood