Intuitively, a variable, such as height, that can take various values in a population, and such that some values have some probability of occurrence, and others a different probability (for example, there might be a probability of one in ten that a person is 5' 8'' tall, but only one in one hundred that they are 6' 8'' tall). In probability theory a random variable is a variable X that can take any one of a finite or countably infinite range of values, each with a probability. The distribution of a random variable is the set of pairs (x i, Prob X = x i), giving the probability associated with each value in the range. In the example, (5' 8'', 0.1) would be one member of the distribution of the random variable of height in a population, if 10% of the population is 5' 8'' tall.
Philosophy dictionary. Academic. 2011.