A javelin is a sharp-tipped, lightweigh throwing spear that's used in sporting events. The javelin throw is an event in the Olympics.
Historically, the javelin was used as a weapon. African and Zulu tribes have used javelins, as well as Welsh fighters and ancient Roman Empire and Anglo-Saxon soldiers. More recently, javelins are simply thrown for sport. The Middle French javeline is a diminutive form of the Old French javelot, or "spear." The ultimate root is probably the Proto-Indo-European word ghabholo, "a fork or branch of a tree."