Definitions of risk:

• noun:   a venture undertaken without regard to possible loss or injury

  Example: "He saw the rewards but not the risks of crime"

• noun:   the probability of being exposed to an infectious agent
• noun:   the probability of becoming infected given that exposure to an infectious agent has occurred
• noun:   a source of danger; a possibility of incurring loss or misfortune
• verb:   expose to a chance of loss or damage

  Example: "We risked losing a lot of money in this venture"

• verb:   take a risk in the hope of a favorable outcome
• name:  A surname (rare: 1 in 100000 families; popularity rank in the U.S.: #16754)