cumulus
Americannoun
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a heap; pile.
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a cloud of a class characterized by dense individual elements in the form of puffs, mounds, or towers, with flat bases and tops that often resemble cauliflower: as such clouds develop vertically, they form cumulonimbus.
noun
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A dense, white, fluffy cloud with a flat base, a multiple rounded top, and a well-defined outline. The bases of cumulus clouds form primarily in altitudes below 2,000 m (6,560 ft), but their tops can reach much higher. Cumulus clouds are generally associated with fair weather but can also bring rain when they expand to higher levels. The clouds' edges are well-defined when they are composed of water droplets and fuzzy when made up of ice crystals.
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See illustration at cloud
Other Word Forms
Noun Inflected Forms
Etymology
Origin of cumulus
1650–60; < New Latin ( Latin: mass, pile)
Vocabulary lists containing cumulus
Weather and Climate - Introductory
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Weather and Climate - Middle School
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Earth Science - Middle School
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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.
The weather rules include atmospheric electricity, types of cloud, specifically cumulus and disturbed weather like rain or strong winds.
From BBC • Mar. 30, 2026
The company said "cumulus cloud rule" complicated the launch and they were "reviewing opportunities for our next launch attempt based on forecasted weather."
From Barron's • Nov. 9, 2025
A recent study found that after 15 percent of the sun becomes obscured, cumulus clouds, the small cotton ball-like ones typical for a sunny day, can dissipate.
From New York Times • Apr. 8, 2024
As that sinister cumulus rose above an oval-shaped reservoir, it collapsed, sending red-hot embers down the steep slopes toward Greenville in a storm of torched trees and exploding shrubs.
From Salon • Jun. 6, 2023
Herds of puffy cumulus raced beneath the sun, imprinting the landscape with a shifting matrix of shadow and blinding light.
From "Into Thin Air" by Jon Krakauer
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.
