cir·​rus | \ˈsir-əs \
plural cirri\ˈsir-​ˌī \

Definition of cirrus 

1 : tendril

2 : a slender usually flexible animal appendage or projection: such as

a : an arm of a barnacle

b : a filament of a crinoid

c : a fused group of cilia functioning like a limb on some protozoans

d : the male copulatory organ of various invertebrate animals

3 : a high wispy white cloud usually of minute ice crystals formed at altitudes between about 20,000 and 40,000 feet (6,000 and 12,000 meters) — see cloud illustration

Examples of cirrus in a Sentence

Recent Examples on the Web

The alto cirrus indicate a change in weather, the mare’s tail mean high-altitude winds, the cumulus means building moisture. Tom Stienstra, San Francisco Chronicle, "Nature’s fortune-tellers predicted wild weather for Memorial Day weekend," 28 May 2018 There were just a few wispy cirrus clouds in the bright blue sky, but that was enough to spark a fire rainbow. Caitlin O'kane, CBS News, ""Fire rainbow" spotted in Vermont – what is this colorful phenomenon?," 11 June 2018 At sunset, a mix of alto cirrus with mare�s tails and cumulus provide a backdrop to pristine Forester Lake at 10, 240 feet, nestled in the Great Western Divide. Tom Stienstra, San Francisco Chronicle, "Nature’s fortune-tellers predicted wild weather for Memorial Day weekend," 28 May 2018 Dense forest had suddenly given way to a lake flanked by mountains — a Chia pet landscape of undulating greenery beneath a vivid blue sky streaked with cirrus clouds. Jada Yuan, New York Times, "Place 11 of 52: In Chile, a Gorgeous, Very Rainy and Sometimes Lonely Journey," 8 May 2018 Clouds come in all shapes and sizes: wispy, high cirrus, puffy cumulus, the low, gray stratocumulus layers that blanket gloomy days. Kate Marvel, Scientific American, "Will Changing Cloud Cover Accelerate Global Warming?," 8 Dec. 2017 For example, thin, wispy cirrus clouds, the most common type of high cloud, are difficult to spot against a background of snow, according to NASA. Alessandra Potenza, The Verge, "NASA wants your help checking its satellites — so send in your cloud pics," 16 Mar. 2018 In addition to educational aims, OreSat will map high altitude cirrus clouds in an effort to better understand their role in climate change, and also test a Wi-Fi signal from space. Samantha Swindler,, "Can Oregon's first nano-satellite, OreSat, get students interested in space? (Column)," 10 Jan. 2018 Clouds are classified into 10 basic genera—such as cirrus and cumulonimubus—which describe their overall character, reports Stephanie Pappas at LiveScience. Jason Daley, Smithsonian, "Cloud Atlas Adds First New “Species” in Almost 70 Years," 24 Mar. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'cirrus.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of cirrus

1708, in the meaning defined at sense 1

History and Etymology for cirrus

New Latin, from Latin, curl

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Time Traveler for cirrus

The first known use of cirrus was in 1708

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English Language Learners Definition of cirrus

: a thin type of cloud that forms high in the sky


cir·​rus | \ˈsir-əs \
plural cirri\ˈsir-​ī \

Kids Definition of cirrus

: a thin white cloud of tiny ice crystals that forms at a very high altitude


cir·​rus | \ˈsir-əs \
plural cirri\ˈsi(ə)r-​ˌī \

Medical Definition of cirrus 

: a slender usually flexible animal appendage: as

a : a fused group of cilia functioning like a limb on some protozoans

b : the male copulatory organ of some worms

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More from Merriam-Webster on cirrus

Rhyming Dictionary: Words that rhyme with cirrus

Spanish Central: Translation of cirrus

Nglish: Translation of cirrus for Spanish Speakers

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