horsetail

noun

1. The tail of a horse.

2. Any of various simple vascular plants, of the order Equisetales, that have hollow stems and produce spores.

3. A Turkish standard denoting rank.

   Commanders were distinguished by the number of horsetails carried before them. The sultan had seven, the grand vizier five, and the pashas three, two, or one.

4. A mare's tail, a water plant in genus Hippuris.

5. Any waterfall, the descending water of which maintains contact with bedrock most of the time.

6. Cauda equina, a bundle of nerve fibers.

7. A ponytail hairstyle.