unbelievable
Americanadjective
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too dubious or improbable to be believed.
an unbelievable excuse.
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so remarkable as to strain credulity; extraordinary.
the unbelievable fury of the storm; an unbelievable athlete.
adjective
Other Word Forms
Derived Forms
Etymology
Origin of unbelievable
First recorded in 1540–50; un- 1 + believe ( def. ) + -able ( def. )
Explanation
The word unbelievable describes something that is beyond understanding, like the idea, until the Middle Ages, that the earth might actually be round. Unbelievable refers to something that seems incredible (Did you hear the story about the guy who was rescued after being stranded at sea for 6 months on a sailboat?), but it can also refer to something that's so unlikely, so improbable, that you're probably not going to be convinced by it (Hey, did you hear the story about the guy who was rescued after being stranded at sea for 6 months with only a log to keep him afloat?).
Vocabulary lists containing unbelievable
Wow! Synonyms for "Amazing"
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
This might sound unbelievable, but I’ve had many episodes of fear in this process — in manifestos I’ve made, at shows, in recordings.
From Los Angeles Times • Jun. 4, 2026
Despite its huge economy -- California would have the world's fourth largest if it were a country -- and its pockets of unbelievable wealth, America's most populous state is disgruntled.
From Barron's • Jun. 2, 2026
The E Street Band rose to the occasion with an unbelievable amount of energy.
From Salon • May 29, 2026
These things do not have to rewire every element of day-to-day life to be unbelievable.
From Slate • May 24, 2026
If the rats could detect the handful of greens he’d eaten hours earlier, they must have an unbelievable sense of smell.
From "Gregor the Overlander" by Suzanne Collins
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
