Event

A subset of the outcomes of a process. For instance, the set of
outcomes {2, 4, 6} when rolling a die is an event that one might
call "rolling an even number".
Complementary Events

Events whose probabilities add up to 1. Two events are
complementary when one event occurs if and only if the other does not.
Odds

The ratio of the probability of an event to the probability of its
complement; i.e., the ratio of favorable outcomes to
unfavorable outcomes.
Outcomes

The possible results of an event. For example, when a die is rolled,
the possible outcomes are 1, 2, 3, 4, 5, and 6.
Probability

A measure of the likeliness that an event will happen.
Probability = 
