The tail of an animal, bird, or fish is the part extending beyond the end of its body.

You can use tail to refer to the end or back of something, especially something long and thin.

If a man is wearing tails, he is wearing a formal jacket which has two long pieces hanging down at the back.

To tail someone means to follow close behind them and watch where they go and what they do.

A tail is someone who is paid to watch and to follow another person.

If you toss a coin and it comes down tails, you can see the side of it that does not have a picture of a head on it.

If you say that the tail is wagging the dog, you mean that a small or unimportant part of something is becoming too important and is controlling the whole thing.

If you say that you have your tail between your legs, you are emphasizing that you feel defeated and ashamed.

If you turn tail, you turn and run away.