From the the word snipe.
Sniping is the act of firing at a target from a medium to long range, with a firearm or any other ranged weapon. Sniping usually involves a potent bolt action rifle with a scope, although there are semi automatic platforms such as the M82A1, M21. Calibers for these weapons usually include 12.7mm and 7.62mm and more. The art of sniping usually requires two people, spotter and shooter, the spotter usually finds the target and does calculations for wind speed, distance and deviation because of the Coriolis effect. Sniping IS NOT limited to achieving kills with scoped weapons. Marksmen and snipers ARE not the same thing, Marksmen are found within squads. Snipers are found in the company or battallion
As he looked through the scope on his Barret M82A1, he gently squeezed the trigger, in less than a second the head of the man he was sniping burst as if someone had thrown chilli into the air. The spotter smiled as he pat the sniper on the back, enjoying the spectacle