ironman noun4 •(Australia) A form of surf lifesaving competition which combines swimming, board paddling, ski paddling and running. •An extreme form of triathlon, expecially one organised by the World Triathlon Corporation that comprises a 2.4-mile swim, a 112-mile bike race and a marathon run. •An extremely tough and strong athlete, especially one who competes in extreme athletic competitions or in a large number of games consecutively. •The winner of such a lifesaving event or triathlon. formsironmans · ironmen