If you describe someone's character or behaviour as merry, you mean that they are happy and cheerful.

A merry sound or sight makes you feel cheerful.

If you get merry, you get slightly drunk.

Some people use merry to emphasize something that they are saying, often when they want to express disapproval or humour.

Just before Christmas and on Christmas Day, people say 'Merry Christmas' to other people to express the hope that they will have a happy time.

If people make merry, they enjoy themselves and have fun, for example by singing, dancing, and drinking together.