trampoline = T = trap door


1. n. A program interrupt, usually an interrupt caused by some exceptional situation in the user program. In most cases, the OS performs some action, then returns control to the program. 2. vi. To cause a trap. "These instructions trap to the monitor." Also used transitively to indicate the cause of the trap. "The monitor traps all input/output instructions."

This term is associated with assembler programming (`interrupt' or `exception' is more common among HLL programmers) and appears to be fading into history among programmers as the role of assembler continues to shrink. However, it is still important to computer architects and systems hackers (see system, sense 1), who use it to distinguish deterministically repeatable exceptions from timing-dependent ones (such as I/O interrupts).

--Jargon File, autonoded by rescdsk.

In printing terminology it is the overlap of two colors that fit tightly together to prevent a seam from being visible. When printing was more photography based (meaning manually manipulated) creating trap was an ordeal since our stubby little fingers have a hard time dealing with hundredths of an inch. With the popularization of dtp technology creating trap became more of a menu option and less of a headache.

The trap is a simple skill in pinball, yet vital to achieving higher scores and playing a strategy.

To trap, just get the pinball to come to a stop at the bottom of the V-shape formed when the flipper is held in the up position. Then the flipper can be released, and the ball is moving much more slowly, making it easier to aim at a specific target on the playfield. It may also allow the player to catch their breath, take a pause, examine the playfield, and in newer machines, get the status of the goals completed and pending.

The most common way to trap is to just hold the flipper up as the ball comes down the inlane. However, this can be dangerous if the player does not judge the speed properly. It is quite possible for the ball to be going fast enough that just holding up the flipper will merely cause the ball to roll up and over the end of the flipper, with little enough momentum that it will simply drain down the middle.

The trap can also be done by keeping the flipper up as the ball comes down the playfield, where it will bounce off the flipper and up through the inlane. If the ball is going fast enough, it can exit through the top of the inlane. Older machines allowed the ball to come back down through, setting off the trigger again. Newer machines are busy enough that either the ball will deflect into the playfield, or it will come back down through the outlane. This method is thus not recommended on newer machines

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Every water-using fixture in a building is an endpoint to the city water system (or a private water system, in well-fed buildings) and an origin point of a sewer or septic system. The problem with this fact - which greatly slowed the spread of indoor plumbing in the late 18th and early 19th centuries - is that gasses from the sewer system tend to rise and spill out of fixtures connected to it. Anyone who has encountered these gasses can attest to their vile and unhealthy nature, and in the early days of plumbing they could render whole buildings uninhabitable.

A number of solutions were attempted throughout the years, but the most successful (and thus most common today) is the trap, a sideways-S-shaped pipe that - you guessed it - traps the gasses and prevents them from making their way up through the fixture. Basically, there's a dip in the pipe just below the fixture (half of the "S" shape), after which it the pipe turns upwards again (to form the other half of the "S".) This "traps" water in the dip; this water seal prevents the exchange of gasses between the sewer and the air of the building.

Here's some bad ASCII art, which might make things a little clearer:

                          to fixture
                     ___      | |
                    / _ \     | |
                   / / \ \    | |
awful stench -->  / /   \ \   | |
                  | |   |-|   |-|
                  | |   \ \   / /
                  | |    \ \_/ /  <-- water
                  | |     \___/

               to sewer

You'll recognize traps under sinks in your home, where they're plainly visible, but they're also present in any other fixture connected to the sewer system. They may be concealed inside the fixture, behind a wall or under the floor, as in tubs and showers, but trust me - they're there. You'd know if they weren't.

Early traps were problematic - the siphon effect of water flowing into the sewer tended to pull the water seal down with it, or back pressure in the sewer lines would blow the water seal back into the fixture (yech.) In 1874, however, an unidentified but clever plumber realized that the pressure in the sewer-side of the system could be equalized with normal atmospheric pressure by means of a vent pipe. Modern plumbing systems all include a venting system that aggregates the vents from all of the traps in the system to an output (called a "stack vent" or "stink pipe," depending on who you talk to) that can be routed to an inoffensive location (usually the roof). Leaks in this venting system can release foul odors; alternately, if it clogs then traps may lose their water seals and begin to release gas themselves.

The water seal in infrequently-used fixtures may eventually evaporate, with unpleasant results. If a disused sink or tub starts to smell bad, that's probably the cause - just run some water down it to re-establish the seal in the trap.

Sources: Kentucky State Plumbing Code, 815 KAR 20:010 (Section 1, "Definition of Terms,")
"Plumbing Care & Repair Handbook,"
"The New World: Plumbing History,"

To understand trap; to know one's own interest.

The 1811 Dictionary of the Vulgar Tongue.

Constables and thief-takers. CANT.

The 1811 Dictionary of the Vulgar Tongue.

Trap (?), v. t. [imp. & p. p. Trapped (?); p. pr. & vb. n. Trapping.] [Akin to OE. trappe trappings, and perhaps from an Old French word of the same origin as E. drab a kind of cloth.]

To dress with ornaments; to adorn; -- said especially of horses.

Steeds . . . that trapped were in steel all glittering. Chaucer.

To deck his hearse, and trap his tomb-black steed. Spenser.

There she found her palfrey trapped In purple blazoned with armorial gold. Tennyson.


© Webster 1913.

Trap, n. [Sw. trapp; akin to trappa stairs, Dan. trappe, G. treppe, D. trap; -- so called because the rocks of this class often occur in large, tabular masses, rising above one another, like steps. See Tramp.] Geol.

An old term rather loosely used to designate various dark-colored, heavy igneous rocks, including especially the feldspathic-augitic rocks, basalt, dolerite, amygdaloid, etc., but including also some kinds of diorite. Called also trap rock.

Trap tufa, Trap tuff, a kind of fragmental rock made up of fragments and earthy materials from trap rocks.


© Webster 1913.

Trap, a.

Of or pertaining to trap rock; as, a trap dike.


© Webster 1913.

Trap, n. [OE. trappe, AS. treppe; akin to OD.trappe, OHG. trapo; probably fr. the root of E. tramp, as that which is trod upon: cf. F. trappe, which is trod upon: cf. F. trappe, which perhaps influenced the English word.]


A machine or contrivance that shuts suddenly, as with a spring, used for taking game or other animals; as, a trap for foxes.

She would weep if that she saw a mouse Caught in a trap. Chaucer.


Fig.: A snare; an ambush; a stratagem; any device by which one may be caught unawares.

Let their table be made a snare and a trap. Rom. xi. 9.

God and your majesty Protect mine innocence, or I fall into The trap is laid for me! Shak.


A wooden instrument shaped somewhat like a shoe, used in the game of trapball. It consists of a pivoted arm on one end of which is placed the ball to be thrown into the air by striking the other end. Also, a machine for throwing into the air glass balls, clay pigeons, etc., to be shot at.


The game of trapball.


A bend, sag, or partitioned chamber, in a drain, soil pipe, sewer, etc., arranged so that the liquid contents form a seal which prevents passage of air or gas, but permits the flow of liquids.


A place in a water pipe, pump, etc., where air accumulates for want of an outlet.


A wagon, or other vehicle.




A kind of movable stepladder.


Trap stairs, a staircase leading to a trapdoor. -- Trap tree Bot. the jack; -- so called because it furnishes a kind of birdlime. See 1st Jack.


© Webster 1913.

Trap (?), v. t. [AS. treppan. See Trap a snare.]


To catch in a trap or traps; as, to trap foxes.


Fig.: To insnare; to take by stratagem; to entrap.

"I trapped the foe."



To provide with a trap; to trap a drain; to trap a sewer pipe. See 4th Trap, 5.


© Webster 1913.

Trap, v. i.

To set traps for game; to make a business of trapping game; as, to trap for beaver.


© Webster 1913.

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