switch

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An exchange or a swap, especially one done secretly.
• noun A transference or shift, as of opinion or attention.
• noun A device used to break or open an electric circuit or to divert current from one conductor to another.
• noun A device consisting of two sections of railroad track and accompanying apparatus used to transfer rolling stock from one track to another.
• noun A slender flexible rod, stick, or twig, especially one used for whipping.
• noun The bushy tip of the tail of certain animals.
• noun A thick strand of real or synthetic hair used as part of a coiffure.
• noun A flailing or lashing, as with a slender rod.
• intransitive verb To exchange.
• intransitive verb To shift, transfer, or divert.
• intransitive verb To connect, disconnect, or divert (an electric current) by operating a switch.
• intransitive verb To cause (an electric current or appliance) to begin or cease operation.
• intransitive verb Informal To produce as if by operating a control. Often used with on.
• intransitive verb To move (rolling stock) from one track to another; shunt.
• intransitive verb To whip with a switch, especially in punishing a child.
• intransitive verb To jerk or swish abruptly or sharply.
• intransitive verb To make or undergo a shift or an exchange.
• intransitive verb To swish sharply from side to side.

from The Century Dictionary.

• To strike with a small twig or rod; beat; lash; hence, to cut or drive as with a switch.
• To swing; whisk.
• To trim, as a hedge.
• In railroading, to transfer by a switch; transfer from one line of rails to another.
• In electricity, to shift to another circuit; shunt.
• To cut at; strike at.
• To move off on a switch, or as if on a switch.
• noun A small flexible twig or rod.
• noun A mechanical device for shifting a moving body, or a current of electricity, etc., from one course or track to another.
• noun In some forms of gas-burner, a key for controlling the amount of gas allowed to pass through.
• noun The act of operating a switch: as, to make a flying switch. See phrase below.
• noun 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.
• noun . 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.

from the GNU version of the Collaborative International Dictionary of English.

• intransitive verb Prov. Eng. To walk with a jerk.
• noun A small, flexible twig or rod.
• noun (Railways) A movable part of a rail; or of opposite rails, for transferring cars from one track to another.
• noun A separate mass or trees of hair, or of some substance (at jute) made to resemble hair, worn on the head by women.
• noun (Elec.) A device for shifting an electric current to another circuit, or for making and breaking a circuit.
• noun (Railways) a form of switch contrived to prevent or lessen the danger of derailment of trains.
• noun (Railways) an arrangement of tracks whereby elevations otherwise insurmountable are passed. The track ascends by a series of zigzags, the engine running alternately forward and back, until the summit is reached.
• noun (Elec.) a collection of switches in one piece of apparatus, so arranged that a number of circuits may be connected or combined in any desired manner.
• noun (Bot.) See under Grass.
• transitive verb To strike with a switch or small flexible rod; to whip.
• transitive verb To swing or whisk.
• transitive verb Prov. Eng. To trim, .