rattail

plural rattails · alternative rat-tail

1. Any of the large dark-colored deep-sea fish of the Macrouridae family of ray-finned fish.

   In the North Atlantic, Russians pioneered the harvesting of rattails, a ubiquitous deep fish with big eyes and a long tail that swishes back and forth in a sinuous motion.

   1995 December 26, William J. Broad, “Creatures of the Deep Find Their Way to the Table”, in The New York Times

   Synonyms: grenadier, macrourid, whiptail

2. A fish, a California chimera (Hydrolagus colliei, syn. Chimaera colliei).
3. A hairstyle characterized by a long lock of tail-like hair dangling from the back of the head; the dangling lock itself.

   All of which could explain why, when I had my hair styled in a tight ponytail for the shoot accompanying this feature, most people who saw me thought I looked "unapproachable" (which might simply be a polite way of saying: "You looked like you had a rattail and a Croydon facelift").

   2013 July 28, Elizabeth Day, The Observer

4. A type of file (cutting tool) with a round cross section and usually also a taper toward the distal end.

   Synonyms: rat-tail file

5. slangA towel that has been tightly twisted along the diagonal to make a rudimentary whip with a towel corner at the tip, typically used in juvenile pranks.
6. An excrescence growing from the pastern to the middle of the shank of a horse.
7. The flowering plant Stachytarpheta cayennensis.