unless

[ uhn-les, uhn- ]

See synonyms for unless on Thesaurus.com

conjunction

except under the circumstances that: I'll be there at nine, unless the train is late.

preposition

except; but; save: Nothing will come of it, unless disaster.

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

Words Nearby unless

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use unless in a sentence

unless there is a court decision that changes our law, we are OK.
Jeb Bush’s Unseen Anti-Gay Marriage Emails | Jackie Kucinich | January 9, 2015 | THE DAILY BEAST
It is grandstanding for a right rarely protected unless under immediate attack.
Politicians Only Love Journalists When They're Dead | Luke O’Neil | January 8, 2015 | THE DAILY BEAST
They had rarely seen their own fathers carry small children unless their mothers were ill.
How Good Dads Can Change the World | Gary Barker, PhD, Michael Kaufman | January 6, 2015 | THE DAILY BEAST
Which is impossible unless people talk publicly rather than letting each crime be its own isolated incident.
Cover-Ups and Concern Trolls: Actually, It's About Ethics in Suicide Journalism | Arthur Chu | January 3, 2015 | THE DAILY BEAST
In some ways I never got out of that unless realizing… well, that kind of seals it off.
The Story Behind Lee Marvin’s Liberty Valance Smile | Robert Ward | January 3, 2015 | THE DAILY BEAST

For instance, the Limestone Polypody is not happy unless there is a certain amount of lime present in the soil.
How to Know the Ferns | S. Leonard Bastin
This was why we resolved, at the time of our arrival, not to baptize any adults unless they were previously well catechized.
The Jesuit Relations and Allied Documents, Vol. II: Acadia, 1612-1614 | Various
However great the power of Revival, there is no memory unless there was a First Impression.
Assimilative Memory | Marcus Dwight Larrowe (AKA Prof. A. Loisette)
If we set him adrift the poor child would starve—unless the cat got him.
The Tale of Grandfather Mole | Arthur Scott Bailey
The intensity of his sensations seemed inexplicable, unless some reality, some truth, lay behind them.
The Wave | Algernon Blackwood

British Dictionary definitions for unless

unless

/ (ʌnˈlɛs) /

conjunction

(subordinating) except under the circumstances that; except on the condition that: they'll sell it unless he hears otherwise

preposition

rare except

Origin of unless

C14: onlesse, from on on + lesse less; compare French à moins que, literally: at less than

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

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