From Longman Dictionary of Contemporary Englishdecathlonde‧cath‧lon /dɪˈkæθlɒn, -lən $ -lɑːn, -lən/ noun [singular] DSOa sports competition with 10 different events → pentathlon, triathlon
Examples from the Corpus
decathlon• His thoughts had run the gamut during lunch, competing in an emotional decathlon.• Peters and Daley Thompson, the 1980 and 1984 Olympic decathlon champion, were there to cheer her on.• Anthony Brannen will have to produce another inspired second day performance today to keep his Olympic decathlon hopes alive.• It would have to be the decathlon for its tradition and unchanging scale of requirements.Origin decathlon (1900-2000) deca- + Greek athlon “competition” 