snip·er
A skilled military shooter detailed to spot and pick off enemy soldiers from a concealed place.
One who shoots at other people from a concealed place.
A sniper rifle by definition is a rifle used by a skilled military shooter or by someone from a concealed position to shoot at people.
It gripes me to no end to hear some one ask "What's a good "SNIPER" rifle?" You have to ask yourself; "What the hell are they planning on doing?"...