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

cirrus clouds

a slender tendril or hairlike filament, such as the appendage of a barnacle, the barbel of a fish, or the intromittent organ of an earthworm