I've been using Worldcraft, trying to make any kind of worthwhile map for Half-Life, and I've discovered another use of the word prefab. It's a lot like what's outlined above, except they're prefabricated items in levels -- like houses, planes, stairs, elevators, explosive gorillas; Want a gazebo but don't wanna build it yourself? Look online for the prefab! Too lazy to make that 4000-polygon F-15? Import the prefab! You too can be lazy and have a gimmick-filled map!

It should be noted that a lot of the prefabs are things such as doors and ceiling lights -- those are included so that you don't have to create four dozen doors, then link them to thefunc_door entity, add a rotating point or trigger to open it if you must, et cetera. These can actually save a lot of time. The gun turret (referred to in the game as "TANK"s and controls) saves a crapload of time, too, unless you need to rotate the gun 180 degrees, and the bullets fire AT the player using the tank... not like I do that intentionally or anything *grin*.