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; on, less

Example Sentences

But they can’t stop their teen’s trades or withdrawals unless they close the account.

From The Wall Street Journal • Apr. 14, 2026

She did not need to retell this story; she could have left it out completely, and unless you had been there, you wouldn’t have known that it ever happened.

From Salon • Apr. 14, 2026

If she survives the term, the coverage typically ends without value unless it converts to renewable term life; then, the premiums would increase.

From MarketWatch • Apr. 14, 2026

“We wouldn’t see that unless pathogens were jumping from animals to humans.”

From Los Angeles Times • Apr. 13, 2026

He never comes into my room unless he needs something.

From "Red Flags and Butterflies" by Sheryl Azzam