Definition of cirrus in English:



  • 1[mass noun] Cloud forming wispy filamentous tufted streaks or ‘mare's tails’ at high altitude (usually 5 to 13 km, 16,500 to 45,000 ft)

    ‘long strands of high cirrus stretched across the eastern sky’
    [as modifier] ‘cirrus clouds’
    • ‘And from that perspective, you're looking at the very high cirrus clouds over the top of the storm.’
    • ‘There were some high cirrus clouds earlier and it looks like they're coming back, but, for the most part, it's just been beautiful.’
    • ‘Thin strands of cirrus cloud glowed red as the sun rose.’
    • ‘The purpose of the mission was to study cirrus clouds, to improve forecasts of future climate change.’
    • ‘The basic cloud forms are cumulus, which are heaped clouds; stratus, which are layer clouds; and cirrus, which are wispy.’
    • ‘Above us the boundless blue sky was punctuated with a few fluffy cirrus clouds and the sun shining down on all of it.’
    • ‘Haloes can sometimes be a sign that rain is approaching, as cirrus clouds can mean that a frontal system is on its way.’
    • ‘High, tropical cirrus clouds are made up of tiny ice crystals that float at altitudes from 20,000 feet to 60,000 feet.’
    • ‘There have been few days without the presence of cirrus clouds.’
    • ‘I lay on the bed and watched cirrus clouds drift slowly across the sky.’
    • ‘Wispy cirrus clouds are the only ones that form naturally at the high altitudes where jets cruise.’
    • ‘Most halos appear as bright white rings but in some instances, the dispersion of light as it passes through ice crystals found in upper level cirrus clouds can cause a halo to have color.’
    • ‘The persistent cirrus clouds indicate atmospheric turmoil at the levels where such control begins.’
    • ‘A few cirrus clouds floated by, turning dark and blue around the edges.’
    • ‘The formation of wispy cirrus clouds is not a simple matter.’
    • ‘The arc isn't a rainbow in the traditional sense - it is caused by light passing through wispy, high-altitude cirrus clouds.’
    • ‘In the troposphere, water exists as vapor in air, as liquid droplets in clouds, and as frozen ice particles in high altitude cirrus clouds.’
    • ‘Over a distant horizon line, cirrus clouds fill the summer sky.’
    • ‘The lowest of these clouds is nacreous, which normally forms between 10 and 20 miles above the Earth (compared with ice cloud cirrus at around 6 miles).’
    • ‘High cirrus clouds form white streaks across its surface and a number of dark storms act as flaws and focus for the eye.’
  • 2Zoology
    A slender tendril or hair-like filament, such as the appendage of a barnacle, the barbel of a fish, or the intromittent organ of an earthworm.

    • ‘Other common elements may include the possession of fixed conical teeth and cirri, or fleshy hair-like projections, on the head.’
    • ‘The ventral nerve chord and nerve bundles of the maxillary cirri are indicated.’
    • ‘Once the barnacles extended their cirri (fanlike, food-gathering appendages) and started waving them about to collect nutritious particles in the water, the researchers cast a shadow over them with a piece of cardboard.’
    • ‘The diagnosis of this genus is largely based on features of the cirri and arms, and is thus of only limited relevance to the present specimen.’
    • ‘The head is often blunt and typically adorned with tentacles or cirri.’
    1. 2.1Botany A tendril.


Early 18th century (in the sense ‘tendril’): from Latin, literally a curl.