nebulous
Americanadjective
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hazy, vague, indistinct, or confused.
a nebulous recollection of the meeting; a nebulous distinction between pride and conceit.
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cloudy or cloudlike.
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of or resembling a nebula or nebulae in deep space; nebular.
adjective
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lacking definite form, shape, or content; vague or amorphous
nebulous reasons
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of, characteristic of, or resembling a nebula
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rare misty or hazy
Other Word Forms
Etymology
Origin of nebulous
First recorded in 1375–1425; late Middle English, from Latin nebulōsus “full of mist, foggy, cloudy,” from nebul(a) “cloud, mist, vapor” ( see nebula) + -ōsus -ous
Explanation
Something that's nebulous is clouded or hazy. When you walk through the woods on a foggy morning, the trees may all have a mysterious, nebulous look to them. When you fly in a plane on an overcast day, the land below you looks nebulous and indistinct. You can also use nebulous in a more figurative way, to describe vague ideas or fuzzy concepts. Nebulous comes from the Latin nebulosus, "cloudy, misty, or foggy." Its root is nebula, which is "vapor or fog" in Latin and was adopted by astronomers in the 1700s to mean "a cloud of gas and dust in outer space."
Vocabulary lists containing nebulous
To Kill a Mockingbird
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The Great Gatsby
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1984
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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.
Most people react in similarly positive ways, expressing empathy or, my personal favorite, commiserating with me over their own nebulous medical conditions.
From Slate • May 23, 2026
"Once again, the nebulous Boko Haram terrorist group carried out a cowardly attack last night on our military base at Barka Tolorom," Chadian President Mahamat Idriss Deby Itno said on Tuesday in a Facebook post.
From Barron's • May 5, 2026
Efforts to track groups whose hate might turn violent are further complicated by the nebulous, ever-shifting nature of extremism on social media.
From Los Angeles Times • May 1, 2026
At Davos, Trump also signed the charter of his inaugural “Board of Peace,” a nebulous body which may be intended as a rival to the United Nations.
From Salon • Jan. 25, 2026
Millions of worlds are born, evolve, and pass away into nebulous, unmeasured skies; and there is still eternity.
From "Bless Me, Ultima" by Rudolfo Anaya
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.
