horsetail

Short definition from Wiktionary

Noun

1. 1
   A tail of a horse.
2. 2
   Any of various simple vascular plants, of the order Equisetales, that have hollow stems and produce spores.
3. 3
   A Turkish standard denoting rank.
4. 4
   A mare's tail, a water plant in genus Hippuris.
5. 5
   Any waterfall, the descending water of which maintains contact with bedrock most of the time.
6. 6
   cauda equina, a bundle of nerve fibers.
7. 7
   A ponytail hairstyle.