A) to come down from a very high place, such as while climbing a mountain or flying in an airplane

B) the most painful part of most drug use

C) Nowhere near the same as "Dissent", like the moron in the first response would have us believe

A flight simulation game where your only objective is to blow up robots and reactors, then escape from the underground mines before the reactor melts down.

It's a mindless game, but pretty fun.
There is also, Descent II, and Descent 3.

A first-person shooter/shoot ‘em up released in 1995. One of the earliest PC games to feature fully 3D graphics, predating Quake. Descent was unique in that it played deceptively like a space combat sim with similar control layouts, it pioneered 6-degrees-of-freedom gameplay; there is no determined "up" or "down", as your small and maneuverable fighter craft can move left right up or down, turn 360 degrees in all direction and even roll all while doing any of the other things. Taking the role of the Material Defender “Vertigo One”, you explore extraterrestrial mining installations and fight virus infected mining robots, with the goal of destroying the reactor that controls them and rescuing surviving miners along the way. More “Doom but you fly” than Star Wars™ X-Wing, Descent was immediately recognized for its unique gameplay and 3D graphics, and became a critical and commercial success, it is now considered a classic.

Descent spawned two sequels and several expansion packs, before becoming a dormant franchise for sixteen years until recently.

Referring to the infamous staircase descent in chick-flick movies, in which the female lead, usually in slow motion, walks down the staircase, looking totally beautiful, or in mockery, totally ugly, and falls. Generally before a party or school dance. Mocked in several movies, and has been noted in television as well as real life. You know you want it. But you can't have it.

a kickass mason-dixon metal band from Louisville, KY.

A mediocre horror movie with plenty of blood, but not enough ass. The basic plot is as follows:

"Hey guys, lets go spelunking....who's this butch that every viewer is going to think is a lesbian, but because it is a below-average movie, we are going to deny them the gratification of seeing girl on girl action deep underground? And wtf.. we're getting chased by mutant miners? Ok i'll buy that.. so apparently, after escapting from the cave, the ghost of my previously wtfpwned daughter suddenly appears in my car! Liek OMG!

The point in flight where an aircraft starts its descent from the cruise towards the airport.

The third in the trillogy, Descent 3 comes with a more intense (and actual) storyline in which PTMC is convicted of conspiracy by the recently rescued material defender, Vertigo 1 and his team.

Descent 3 has the most played multiplayer, and best graphics.

Sequel to Descent.

Descent II is basically they same as Descent, but with different enviornments, and a few new robots.

Descent II is the last game before the makers at Interplay decided to step up the pixel graphics in Descent 3.