switch

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A slender flexible rod, stick, or twig, especially one used for whipping.
2. n. The bushy tip of the tail of certain animals: a cow's switch.
3. n. A thick strand of real or synthetic hair used as part of a coiffure.
4. n. A flailing or lashing, as with a slender rod.
5. n. A device used to break or open an electric circuit or to divert current from one conductor to another.
6. n. A device consisting of two sections of railroad track and accompanying apparatus used to transfer rolling stock from one track to another.
7. n. The act or process of operating a switching device.
8. n. The result achieved by such an act.
9. n. An exchange or a swap, especially one done secretly.
10. n. A transference or shift, as of opinion or attention.
11. v. Chiefly Southern U.S. To whip with or as if with a switch, especially in punishing a child.
12. v. To jerk or swish abruptly or sharply: a cat switching its tail.
13. v. To shift, transfer, or divert: switched the conversation to a lighter subject.
14. v. To exchange: asked her brother to switch seats with her.
15. v. To connect, disconnect, or divert (an electric current) by operating a switch.
16. v. To cause (an electric current or appliance) to begin or cease operation: switched the lights on and off.
17. v. Informal To produce as if by operating a control. Often used with on: switched on the charm.
18. v. To move (rolling stock) from one track to another; shunt.
19. v. To make or undergo a shift or an exchange: The office has switched to shorter summer hours.
20. v. To swish sharply from side to side.
21. switch off Informal To stop paying attention; lose interest.

Century Dictionary and Cyclopedia

1. n. A small flexible twig or rod.
2. n. A mechanical device for shifting a moving body, or a current of electricity, etc., from one course or track to another. Specifically— In railroads, in its simplest form, two parallel lengths of rails joined together by rods, pivoted at one end, and free to move at the other end, forming a part of the track at its junction with a branch or siding. The switch-rails rest on metal plates laid on the sleepers, and, by means of a rod fastened to their free ends, can be moved sidewise. The ends of the next pair of rails and the ends of the first pair of the siding or branch are placed side by side, so that by the movement of the switch either pair may be brought in line with the track, and any car or engine passing the switch will be guided upon the rails to which the switch is directed. Such a switch may be used to connect several lines of rails. The objection to this form of switch is that a car moving on a track not connected with the switch is liable to be derailed by running off the open ends of the track. This has led to the adoption of safety-switches, of which there are various forms. One of the most common of these is the split switch, in which the ends of the rails, instead of being square, are drawn out (split) to a thin edge so as to lie close against the side of the next rail. The narrow rails used are flexible and are fitted with springs, so that in the event of a displacement of the switch the lateral pressure of the wheels will cause the points to move back and thus keep the wheels on the line, the points returning to their original position by the recoil of the springs. Another form of safety-switch is designed to keep unbroken the track of the main line, so that the main-line rails are not cut at all. To use this form of switch the levers are moved, and the car rises on an inclined rail and passes over the main rails to the siding. A great number of devices have been invented to make switches more safe, to render them automatic (as at the terminus of a line where the engine is to be shifted to the other end of a train), to render them interlocking, so that no one switch of a system can be opened without locking all others, and to connect them with signals and annunciators. Switches in one yard are now commonly controlled by means of long levers with a central tower from which one switchman can see and control them all.
3. n. In some forms of gas-burner, a key for controlling the amount of gas allowed to pass through.
4. n. The act of operating a switch: as, to make a flying switch. See phrase below.
5. n. A quantity of long hair, secured together at one end, worn by women with their own hair to make it look thicker. Jute or yak is sometimes used with or in place of hair, being cheaper.
6. To strike with a small twig or rod; beat; lash; hence, to cut or drive as with a switch.
7. To swing; whisk.
8. To trim, as a hedge.
9. In railroading, to transfer by a switch; transfer from one line of rails to another.
10. In electricity, to shift to another circuit; shunt.
11. To cut at; strike at.
12. To move off on a switch, or as if on a switch.
13. n. . In electricity, a device for opening or closing an electric circuit, for reversing the direction of the current in such a circuit, for shifting current from one branch of a circuit to another, or, in general, for making, breaking, or shifting electrical connections. Switches vary greatly in design according to the conditions to be met. In general a switch differs from a key (which is a device for the easy and rapid making or breaking of a circuit, as in telegraphic signaling) in that it is so constructed that the circuit when broken shall remain open and when made shall remain closed until the reverse operation is performed. A switch should be so constructed as to carry permanently without excessive heating the maximum eurrent of the circuit in which it is placed, and the contacts should be of such low resistance that they will not become appreciably hot on the passage of the current. Good contact is sometimes secured by the use of a ‘mercury-switch’ in which the terminals of the lines to be connected are permanently attached to metallic capsules filled with mercury. When the circuit is to be closed connection between the mercury-cups is made by means of a short copper bar or link with ends bent downward so as to dip into the mercury. The volatilization of the mercury by the spark formed when the circuit is opened is a serious objection to mercury-switches and the ‘knife-switch’ is therefore more frequently used. It consists of a strip of copper, the knife, hinged at one end, or sometimes of two or more such knives mounted parallel to one another. The free end of the knife enters with considerable friction between the jaws of a copper clip when the circuit is to be closed, the friction serving to secure good contact between the metallic surfaces and to bold the knife in place. On high-tension circuits various devices are employed to prevent the formation of an arc when the circuit is open or to extinguish the arc when formed. One such device is the ‘snap-switch,’ in which, in order to make contact, a powerful spring is compressed and the switch is locked by a simple mechanism. When unlocked, the spring opens the switch with great suddenness, and the arc is of short duration. Sometimes a magnetic blow-out is used to extinguish the arc and sometimes an ‘oil-break switch’ is employed in which the opening of the circuit is made under oil. Automatic switches are frequently used in connection with electrical machinery. In the case of such switches the operation, whether it consist of the opening or closing of a circuit, the reversal of current, or the shifting of connections from one circuit to another, is done mechanically, either by the direct action of electromagnets or by mechanism released and set in motion by such magnets or otherwise.

Wiktionary

1. n. A device to turn electric current on and off or direct its flow.
2. n. A change.
3. n. rail transport, US A movable section of railroad track which allows the train to be directed down one of two destination tracks; point.
4. n. A slender woody plant stem used as a whip.
5. n. computer science A command line notation allowing specification of optional behavior.
6. n. computing, programming A programming construct that takes different actions depending on the value of an expression.
7. n. computing, networking A networking device connecting multiple wires, allowing them to communicate simultaneously, when possible. Compare to the less efficient hub device that solely duplicates network packets to each wire.
8. n. telecommunications A system of specialized relays, computer hardware, or other equipment which allows the interconnection of a calling party's telephone line with any called party's line.
9. n. BDSM One who is willing to take either a sadistic or a masochistic role.
10. v. transitive To exchange.
11. v. transitive To change (something) to the specified state using a switch.
12. v. transitive To whip or hit with a switch.
13. v. intransitive To change places, tasks, etc.
14. v. slang (intransitive) To get angry suddenly; to quickly or unreasonably become enraged.

GNU Webster's 1913

1. n. A small, flexible twig or rod.
2. n. (Railways) A movable part of a rail; or of opposite rails, for transferring cars from one track to another.
3. n. A separate mass or trees of hair, or of some substance (at jute) made to resemble hair, worn on the head by women.
4. n. (Elec.) A device for shifting an electric current to another circuit, or for making and breaking a circuit.
5. v. To strike with a switch or small flexible rod; to whip.
6. v. To swing or whisk.
7. v. Prov. Eng. To trim, .
8. v. To turn from one railway track to another; to transfer by a switch; -- generally with off, from, etc..
9. v. (Eccl.) To shift to another circuit.
10. v. Prov. Eng. To walk with a jerk.

WordNet 3.0

1. n. a flexible implement used as an instrument of punishment
2. v. change over, change around, as to a new order or sequence
3. v. cause to go on or to be engaged or set in operation
4. n. hairpiece consisting of a tress of false hair; used by women to give shape to a coiffure
5. n. control consisting of a mechanical or electrical or electronic device for making or breaking or changing the connections in a circuit
6. n. railroad track having two movable rails and necessary connections; used to turn a train from one track to another or to store rolling stock
7. n. a basketball maneuver; two defensive players shift assignments so that each guards the player usually guarded by the other
8. v. flog with or as if with a flexible rod
9. v. make a shift in or exchange of
10. v. exchange or give (something) in exchange for
11. n. the act of changing one thing or position for another
12. v. lay aside, abandon, or leave for another
13. v. reverse (a direction, attitude, or course of action)
14. n. an event in which one thing is substituted for another