Generally speaking, the act of killing someone in a first person shooter game with a one shot gun (sniper rifle, bolt action rifle, etc) without using a telescopic sight or sniper scope. Most commonly, the term is used to mean that you fired such a gun from the hip and killed someone with it, however it can also (debatably) mean that you pulled up iron sights on a sniper rifle / bolt action rifle and then killed someone that way. The term does not apply to shotguns, semi-automatic rifles (unless they can be scoped), or any automatic weapon.

No scoping is generally viewed as an act of skill (or luck, depending on who you talk to and the mechanics of the game you're playing). This is because you are killing someone with one shot through a (usually) large crosshair and also risk exposing yourself if you miss. However, the amount of prestige that is attached to a single no scope depends on the distance and rate of success; i.e. if you no scope once and do this by killing a guy who you are literally next to, that doesn't take much skill, but if you continually no scope guys who are halfway across the map, that's some seriously good shit on your behalf. On a related note, no scope headshots get you some serious prestige if you can pull them off constantly.

A massive dump that takes 10 to 15 times to flush.

A term used in first person shooter gaming; to kill a player with a rifle-type weapon without using the scope.

The act of not scoping to kill an opponent.
Commonly used in Halo with a sniper but not limited to.

No scoping is NOT applicable to weapons where scoping is not required. ex. ak47, m4a1, battle rifle, SMG, etc.

When the male achieves penetration without the assistance of his or his partners hands.

A noscope is pretty self explanatory. It's killing someone without scoping in with a sniper. Noscopes are often tried in the CoD series, especially on MW2 for a game winning killcam. If you get a noscope across map, you're pro. If people think you have an aimbot because the noscope was so awesome, you're offically a legend.

The action usually used in Call Of Duty, When someone jumps off a point in a map, maybe a high ledge and shoots without using the scope for aim assist.