1. a token; indication.

2. any object, action, event, pattern, etc., that conveys a meaning.

3. a conventional or arbitrary mark, figure, or symbol used as an abbreviation for the word or words it represents.

4. a motion or gesture used to express or convey an idea, command, decision, etc.:

Her nod was a sign that it was time to leave.

5. a notice, bearing a name, direction, warning, or advertisement, that is displayed or posted for public view:

a traffic sign; a store sign.

6. a trace; vestige:

There wasn't a sign of them.

7. an arbitrary or conventional symbol used in musical notation to indicate tonality, tempo, etc.