noun

• a possibility due to a favorable combination of circumstances
  "the holiday gave us the opportunity to visit Washington"
• an unknown and unpredictable phenomenon that causes an event to result one way rather than another
  "bad luck caused his downfall"
• a risk involving danger
  "you take a chance when you let her drive"
• a measure of how likely it is that some event will occur; a number expressing the ratio of favorable cases to the whole number of cases possible
  "the probability that an unbiased coin will fall with the head up is 0.5"

verb

• be the case by chance
  "I chanced to meet my old friend in the street"
• take a risk in the hope of a favorable outcome
  "When you buy these stocks you are gambling"
• come upon, as if by accident; meet with
  "We find this idea in Plato"