A tuft, curl, or tendril.
[Latin cirrus, a tuft or curl.]
Cirrus is the meteorological term for those very high, wispy clouds also called mare's tails; cirrocumulus (Latin cumulus, a heap) is a broken layer of high cloud, and cirrostratus (Latin stratus, strewn) a thin, high layer of hazy cloud. Cirrus is also a term in zoology or botany for a tendril, so the form can refer to this, as in cirrose, bearing tendrils. However, cirrhosis, a disease of the liver, comes instead from the Greek kirrhos, tawny, from its colour when affected.