random variable

This term is a technical cornerstone of probability theory and statistics. While the word "variable" usually suggests a value that changes, a random variable is formally a function. It maps the qualitative outcomes of a stochastic process—such as "heads" or "tails"—into quantitative numerical values that can be analyzed mathematically.

In academic and professional contexts, it is distinguished between discrete random variables, which take on countable values, and continuous random variables, which can take any value within an interval. Misusing this term in a non-mathematical context to mean "something that happens by chance" is a common error; it specifically refers to the mapping function, not the event itself.