source of a potential threat

A hazard is something that can be dangerous. Fire, Explosives and Fuel are all examples of hazards. Many chemicals can be a hazard. There are ways to get rid of hazardous things. There are different types of hazards; some can catch things on fire; some can burn skin; some can irritate the eyes, etc.

NFPA diamonds show the hazards for chemicals. The blue square tells how bad it is to your health. The yellow square tells how easily it can react with things. The red square tells how easily it can burn. The white square has any extra hazards. 0 in the squares is least hazardous; 4 is most hazardous.

The term 'hazard' is used in driving instruction, and in some traffic-related laws. It simply means 'something a motorist should notice and drive accordingly'. For example, children playing on the pavement (U.S. = sidewalk; Austr. = footpath) are a potential hazard. If any go into the actual road, then they are a real hazard, and motorist should do whatever is safe.