Source : Webster's Revised Unabridged Dictionary (1913)

Decathlon \De*cath"lon\, n. [See {Deca-}; {Pentathlon}.]
   In the modern Olympic Games, a composite contest consisting
   of a 100-meter run, a broad jump, putting the shot, a running
   high-jump, a 400-meter run, throwing the discus, a 100-meter
   hurdle race, pole vaulting, throwing the javelin, and a
   1500-meter run.

Source : WordNet®

decathlon
     n : an athletic contest consisting of ten different events