cirrus (cir¦rus)

noun (plural cirri /-rʌɪ/)

• 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

• 2 Zoology 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.
• Botany a tendril.