cirrus

American  

[sir-uhs] / ˈsɪr əs /

noun

• cirrus,
  plural
• cirri
  plural

1. Meteorology.

   1. a cloud of a class characterized by thin white filaments or narrow bands and a composition of ice crystals: of high altitude, about 20,000–40,000 feet (6000–12,000 meters).

   2. a cirriform cloud.

2. Botany. a tendril.

3. Zoology.

   1. a filament or slender appendage serving as a foot, tentacle, barbel, etc.

   2. the male copulatory organ of flatworms and various other invertebrates.

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cirrus British  

/ ˈsɪrəs /

noun

1. meteorol a thin wispy fibrous cloud at high altitudes, composed of ice particles

2. a plant tendril or similar part

3. zoology

   1. a slender tentacle or filament in barnacles and other marine invertebrates

   2. a hairlike structure in other animals, such as a filament on the appendage of an insect or a barbel of a fish

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cirrus Scientific  

/ sîr′əs /

• cirri
  plural

1. A high-altitude cloud composed of feathery white patches or bands of ice crystals. Cirrus clouds generally form between 6,100 and 12,200 m (20,000 and 40,000 ft).

2. See illustration at cloud

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Other Word Forms

Noun Inflected Forms

• cirri
  plural
• cirrus
  plural

Etymology

Origin of cirrus

1700–10; < Latin: a curl, tuft, plant filament like a tuft of hair

Example Sentences

See Examples For:

cirrus cirri

The most likely explanation is the presence of thick but uneven water ice clouds, similar to cirrus clouds high in Earth's atmosphere -- an unexpected complication.

From Science Daily ● Apr. 22, 2026

Sun halos are optical illusions created when ice crystals form in the correct shape in the upper atmosphere, usually accompanying thin, wispy cirrus clouds.

From New York Times ● Apr. 15, 2024

The remaining, thinner cirrus clouds would allow more long-wave radiation emanating from Earth to escape to space.

From Scientific American ● Sep. 20, 2023

The wind-shear phenomenon can occur in wispy cirrus clouds or even clear air near thunderstorms, as differences in temperature and pressure create powerful currents of fast-moving air.

From Seattle Times ● Dec. 19, 2022

There were high cumulus clouds and enough cirrus above them so that the old man knew the breeze would last all night.

From "The Old Man and The Sea" by Ernest Hemingway

The observer must watch the formation of cirri, and the different forms of cirro-stratus and stratus, and become familiar with their appearance.

From The Philosophy of the Weather And a Guide to Its Changes by Thomas Belden Butler

Colours.—Valves internally tinted, in parts, grey; peduncle, brown; corium of sack, purplish-brown, of peduncle, rich coppery brown; cirri, banded dorsally, and with the front surfaces of the segments, purplish-brown.

From A Monograph on the Sub-class Cirripedia With Figures of all the Species. by Charles Darwin

Occasionally the storm center is too far to the south or north to cause rains at your locality, but the cirri bank up on the horizon and their lacework covers the sky.

From Reading the Weather by Thomas Morris Longstreth

C, Highly magnified view of one of the cirri.

From Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" by Various

In some of the cirri, several of the basal segments are soldered together.

From A Monograph on the Sub-class Cirripedia With Figures of all the Species. by Charles Darwin