Original: Two common variations on traditional winter biathlon are summer biathlon, where skiing is replaced by a cross-country run, and archery biathlon (or ski archery), where the rifle is replaced by a recurve bow.
Simplified: Biathlon (not to be confused with duathlon) is a term used to describe any sporting event made up of two disciplines. However, biathlon usually refers specifically to the winter sport that combines cross-country skiing and rifle shooting.