Vocabulary

tail [countable]

1

animal

 the part that sticks out at the back of an animal's body, and that it can move:

The dog wagged its tail.

white-tailed/long-tailed etc

a white-tailed eagle

2

aircraft

 the back part of an aircraft

3

shirt

 the bottom part of your shirt at the back, that you put inside your trousers

4

back part

[usually singular] the back or last part of something, especially something that is moving away from you:

We saw the tail of the procession disappearing round the corner.

5

tails

a) [plural] a man's jacket which is short at the front and divides into two long pieces at the back, worn to very formal events [= tailcoat]

b) [uncountable] spoken said when you are tossing a coin (=throwing it up in the air to decide which of two things you will do or choose) [≠ heads]

6

the tail end of something

 the last part of an event, situation, or period of time

7

be on somebody's tail

informal to be following someone closely

8

follow

informal someone who is employed to watch and follow someone, especially a criminal

put a tail on somebody (=order someone to follow another person)

9

turn tail

informal to run away because you are too frightened to fight or attack

10

with your tail between your legs

 embarrassed or unhappy because you have failed or been defeated

11

it's (a case of) the tail wagging the dog

informal used to say that an unimportant thing is wrongly controlling a situation

12

chase tail

American English informal to try to get a woman to have sex with you

Definition from the Longman Dictionary of Contemporary English
Advanced Learner's Dictionary.