A sign is a mark or shape that always has a particular meaning, for example in mathematics or music.

A sign is a movement of your arms, hands, or head which is intended to have a particular meaning.

If you sign, you communicate with someone using sign language. If a programme or performance is signed, someone uses sign language so that deaf people can understand it.

A sign is a piece of wood, metal, or plastic with words or pictures on it. Signs give you information about something, or give you a warning or an instruction.

If there is a sign of something, there is something which shows that it exists or is happening.

When you sign a document, you write your name on it, usually at the end or in a special space. You do this to indicate that you have written the document, that you agree with what is written, or that you were present as a witness.

If an organization signs someone or if someone signs for an organization, they sign a contract agreeing to work for that organization for a specified period of time.

In astrology, a sign or a sign of the zodiac is one of the twelve areas into which the heavens are divided.

If you say that there is no sign of someone, you mean that they have not yet arrived, although you are expecting them to come.

If you say that an agreement is signed and sealed, or signed, sealed and delivered, you mean that it is absolutely definite because everyone involved has signed all the legal documents.