cirrus

noun

1. pl. cirri Biol.
   1. a plant tendril
   2. a flexible, threadlike tentacle or appendage, as the feelers of certain organisms
   3. a cone-shaped cluster of fused cilia, occurring in many species of infusorians
2. pl. cirrusMeteorol. the type of white cloud that resembles a wispy filament, found at high altitudes and consisting of ice crystals