The state or quality of being dangerous.

What is the meaning of dangerousness?

n. the state in which individuals become likely to do harm either to themselves or to others, representing a threat to their own or other people's safety. —dangerous adj.

Is danger countable or uncountable?

1[uncountable] danger (of something) the possibility of something happening that will injure, harm, or kill someone, or damage or destroy something Danger! Keep Out!