The biathlon is a winter sport that combines cross-country skiing and RIFLE shooting. The equipment used for this sport includes a RIFLE, SKI, skis, skied, RIFLES, and AMMO. A RIFLE is a firearm with a long barrel and a shoulder stock, while skis are long, narrow pieces of wood or plastic used for gliding over snow. Skied is the past tense of the verb 'to SKI', and RIFLES is the plural form of RIFLE. AMMO is short for ammunition, which is the projectiles fired from a gun.