Definition of symbol

1. 1 : a graphic representation, either abstract or representational, of a hazardous situation and/or evasive actions to be taken to avoid harm. It may include a description of protective equipment to be used to eliminate or reduce the hazard to an acceptable level. [SEMI S1-90] Also see sign. 2 : in the bar code marking of silicon wafers, a combination of characters, including start/stop characters, quiet zones, data characters and check characters, that are required by a particular symbology and that form a complete scannable entity. [SEMI T1-93]