resistance

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The act or an instance of resisting or the capacity to resist.
2. n. A force that tends to oppose or retard motion.
3. n. An underground organization engaged in a struggle for national liberation in a country under military or totalitarian occupation.
4. n. Psychology A process in which the ego opposes the conscious recall of anxiety-producing experiences.
5. n. Biology The capacity of an organism to defend itself against a disease.
6. n. Biology The capacity of an organism or a tissue to withstand the effects of a harmful environmental agent.
7. n. Electricity The opposition of a body or substance to current passing through it, resulting in a change of electrical energy into heat or another form of energy.

Century Dictionary and Cyclopedia

1. n. The act of resisting; opposition; antagonism. Resistance is passive, as that of a fixed body which interrupts the passage of a moving body; or active, as in the exertion of force to stop, repel, or defeat progress or design.
2. n. The force exerted by a fluid or other medium to retard the motion of a body through it; more generally, any force which always acts in a direction opposite to the residual velocity, or to any component of it: as, resistance to shearing. In a phrase like this, resistance may be defined as a stress produced by a strain, and tending to restoration of figure. But the resistance is not necessarily elastic—that is, it may cease, and as resistance does cease, when the velocity vanishes. In the older dynamical treatises, resistance is always considered as a function of the velocity, except in the case of friction, which does not vary with the velocity, or at least not much. In modern hydrodynamics the viscosity is taken into account, and produces a kind of resistance partly proportional to the velocity and partly to the acceleration. The theory of resistance still remains imperfect.
3. n. In electricity, that property of a conductor in virtue of which the passage of a current through it is accompanied by a dissipation of energy; the transformation of electric energy into heat. It is one of the two elements upon which the strength of an electric current depends when the flow is steady; the other is electromotive force, and the relation between them is generally expressed by the equation C =E/R. which is Ohm's law. Resistance may therefore be defined as the ratio of the electromotive force to the current strength (R =E/C), the flow being assumed to be steady, for simple periodic alternate currents, the resistance increases as therapidlty of alternation increases, and it also depends on the form of the conductor. Resistance to such currents is sometimes called impedance and also virtual resistance, that for steady flow being named ohmic resistance. In general, resistance is proportional to the length of the conductor and inversely proportional to its cross-section. It also varies with the temperature of the conductor, the nature of the material of which it is composed, the stress to which it is subjected, and in some instances with other physical conditions, as in the case of selenium, the resistance of which diminishes as the intensity of the light to which it is exposed increases. It is the reciprocal of conductivity. The unit of resistance is the ohm (which see). The designation resistance is also applied to mils of wire or other material devices which are introduced into electric circnits on account of the resistance which they other to the passage of the current. The resistance of a conductor may be measured by Wheatstone's bridge. This is a device for the accurate comparison of electric resistances, invented by Christie and brought into notice by Wheatstone. It consists essentially of a complex circuit of six conductors, arranged as shown in the cut. A current from the battery B enters at the junction of a and c, and, after dividing into parts depending on the relative resistances of the branches a, b, c, and d, returns to the battery through the junction of & and d. G is a galvanometer joined to the junctions a b and c d. When the relative resistances are such that a: b:: c: d, no current will flow through the galvanometer. If a and b are comparable and adjustable resistances, it is only necessary to establish this condition in order to know the ratio of c to d. Many modifications of the bridge have been devised.
4. n. Synonyms Hindrance, antagonism, check. See appose.
5. n. In naval architecture, the reaction which a vessel opposes to an extraneous force by which it is dragged or driven through the water, and particularly to motion forward in the direction of the length of the vessel. Modern investigation and experimentation in model-basins have led to the division of this resistance into three principal parts. The whole resistance of the vessel as distinguished from its parts is called the total resistance. Frictional resistance is that part due to the fluid friction of the water flowing past the wetted surface of the vessel (see also coefficient of friction ). The eddy-making resistance is that part due to the formation of eddies in the water flowing past the vessel, particularly where the streams unite at the stern and around projections or abrupt breaks in the under-water surface or at the bows in very bluff-bowed vessels. In well-formed ships the eddy-making resistance is a very small part of the total resistance. The wave-making resistance is that part of the resistance caused by the absorption of energy in the formation and maintenance of the systems of waves accompanying a vessel in motion. This part of the resistance is small at low speeds, but at speeds in knots equal to or greater than the square root of the length of the vessel in feet usually forms the greater part of the total resistance. That part of the total resistance remaining after subtraction of the frictional resistance is called the residuary resistance. (See also Froude's law.)
6. n. Resistance to the flow of current which occurs at the surface between conductors in contact, as in the coherer, or between the liquid and the terminal of an electrolyticcell, or between the heated gas in the electric are and the carbon.
7. n. The resistance offered by a dielectric to the passage of an electric current; the ohmic resistance of an insulating substance.

Wiktionary

1. n. The act of resisting, or the capacity to resist.
2. n. physics A force that tends to oppose motion.
3. n. physics Shortened form of electrical resistance.
4. n. An underground organization engaged in a struggle for liberation from forceful occupation.

GNU Webster's 1913

1. n. The act of resisting; opposition, passive or active.
2. n. (Physics) The quality of not yielding to force or external pressure; that power of a body which acts in opposition to the impulse or pressure of another, or which prevents the effect of another power
3. n. A means or method of resisting; that which resists.
4. n. (Elec.) A certain hindrance or opposition to the passage of an electrical current or discharge offered by conducting bodies. It bears an inverse relation to the conductivity, -- good conductors having a small resistance, while poor conductors or insulators have a very high resistance. The unit of resistance is the ohm.

WordNet 3.0

1. n. the degree of unresponsiveness of a disease-causing microorganism to antibiotics or other drugs (as in penicillin-resistant bacteria)
2. n. group action in opposition to those in power
3. n. the capacity of an organism to defend itself against harmful environmental agents
4. n. any mechanical force that tends to retard or oppose motion
5. n. a secret group organized to overthrow a government or occupation force
6. n. the military action of resisting the enemy's advance
7. n. (medicine) the condition in which an organism can resist disease
8. n. an electrical device that resists the flow of electrical current
9. n. (psychiatry) an unwillingness to bring repressed feelings into conscious awareness
10. n. a material's opposition to the flow of electric current; measured in ohms
11. n. the action of opposing something that you disapprove or disagree with