The definition of a triathlon is a race where three different sporting events are done.
A race involving running, swimming and biking is an example of a triathlon.
an endurance race combining three consecutive events (swimming, bicycling, and running)
Origin of triathlontri- + Classical Greek athlon: see athlete
An athletic contest in which participants compete without stopping in three successive events, usually long-distance swimming, bicycling, and running.
Origin of triathlontri– + (dec)athlon.