tail
noun
teɪl 
teɪl of bird/animal/fish
1 [countable] the part that sticks out and can be moved at the back of the body of a bird, an animal or a fishThe dog ran up, wagging its tail.The male has beautiful tail feathers. see also ponytail-tailed
2 (in adjectives) having the type of tail mentioneda white-tailed eagleof plane/spacecraft
3 [countable] the back part of a plane, spacecraft, etcthe tail wing back/end of something
4 [countable] tail (of something) a part of something that sticks out at the back like a tailthe tail of a kite5 [countable] tail (of something) the last part of something that is moving away from youthe tail of the procession see also tail endjacket
6 tails [plural] (also tailcoat [countable]) a long jacket divided at the back below the waist into two pieces that become narrower at the bottom, worn by men at very formal eventsThe men all wore top hat and tails. see also coat-tails, shirt tail compare dinner jacket, morning coatside of coin
7 tails [uncountable] the side of a coin that does not have a picture of the head of a person on it, used as one choice when a coin is tossed to decide something compare heads noun (5)person who follows somebody
8 [countable] (informal) a person who is sent to follow somebody secretly and find out information about where that person goes, what they do, etcThe police have put a tail on him. Idioms
on somebody's tail
(informal) following behind somebody very closely, especially in a carThere's been a white van sitting on my tail for the past ten miles.the tail (is) wagging the dog
used to describe a situation in which the most important aspect is being influenced and controlled by somebody/something that is not as important
turn tail
to run away from a fight or dangerous situation
When they heard the sirens, they turned tail and ran.