reduction

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

• noun The act or process of reducing.
• noun The result of reducing.
• noun The amount by which something is lessened or diminished.
• noun A sauce that has been thickened or concentrated by boiling.
• noun Biology The first meiotic division, in which the chromosome number is reduced.
• noun A decrease in positive valence or an increase in negative valence by the gaining of electrons.
• noun A reaction in which hydrogen is combined with a compound.
• noun A reaction in which oxygen is removed from a compound.
• noun The canceling of common factors in the numerator and denominator of a fraction.
• noun The converting of a fraction to its decimal equivalent.
• noun The converting of an expression or equation to its simplest form.

from The Century Dictionary.

• noun In linguistics, the shortening of a word by apocope.
• noun In cytology, the halving of the number of somatic chromosomes during spermatogenesis and oögenesis.
• noun The act of reducing, or the state of being reduced.
• noun Conversion into another state or form: as, the reduction of a body to powder; the reduction of things to order.
• noun (c.) Diminution: as, the reduction of the expenses of government; the reduction of the national debt; a reduction of 25 per cent. made to wholesale buyers.
• noun Conquest; subjugation: as, the reduction of a province under the power of a foreign nation; the reduction of a fortress.
• noun A settlement or parish of South American Indians converted and trained by the Jesuits.
• noun The bringing of a problem to depend on a problem already solved.
• noun The transformation of an algebraic expression into another of a simpler kind.
• noun The lowering of the values of the numerator and denominator of a fraction, or of the antecedent and consequent of a ratio, by dividing both by the same quantity.
• noun The conversion of a quantity expressed in terms of one denomination so as to express it in terms of another denomination. Ascending reduction is conversion to terms of larger units; descending reduction, conversion to terms of smaller units.
• noun The proof of the conclusion of an indirect syllogism from its premises by means of a direct syllogism and immediate inferences. This is said to be a reduction to the mode of direct syllogism employed.
• noun A direct syllogism proving, by means of conversions and other immediate inferences, that the conclusion of an indirect syllogism follows from its premises.
• noun The act or process of making a copy of a figure, map, design, draft, etc., on a smaller scale, preserving the original proportions; also, the result of this process.
• noun In surg, the operation of restoring a dislocated or fractured bone to its former place.
• noun Separation of a metal from substances combined with it: used especially with reference to lead, zinc, and copper, and also applied to the treatment of iron ore, as when steel is made from it by a direct process.
• noun In astronomy, the correction of observed quantities for instrumental errors, as well as for refraction, parallax, aberration, precession, and nutation, so as to bring out their cosmical significance. A similar process is applied to observations in other physical sciences.
• noun In Scots law, an action for setting aside a deed, writing, etc.
• noun Synonyms Lessening decrease, abatement, curtailment, abridgment, contraction. retrenchment.

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

• noun The act of reducing, or state of being reduced; conversion to a given state or condition; diminution; conquest
• noun (Arith. & Alg.) The act or process of reducing. See Reduce, v. t., 6. and To reduce an equation, To reduce an expression, under Reduce, v. t.
• noun The correction of observations for known errors of instruments, etc.
• noun The preparation of the facts and measurements of observations in order to deduce a general result.
• noun The process of making a copy of something, as a figure, design, or draught, on a smaller scale, preserving the proper proportions.
• noun (Logic) The bringing of a syllogism in one of the so-called imperfect modes into a mode in the first figure.
• noun (Chem. & Metal.) The act, process, or result of reducing{7}.
• noun (Med.) The operation of restoring a dislocated or fractured part to its former place.
• noun (Arith.) the operation of changing numbers of a lower into others of a higher denomination, as cents to dollars.
• noun (Arith.) the operation of changing numbers of a higher into others of a lower denomination, as dollars to cents.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The act, process, or result of reducing.
• noun The amount or rate by which something is reduced, e.g. in price.
• noun chemistry A reaction in which electrons are gained and valence is reduced; often by the removal of oxygen or the addition of hydrogen.
• noun cooking The process of rapidly boiling a sauce to concentrate it.
• noun mathematics The rewriting of an expression into a simpler form.
• noun a transformation of one problem into another problem, such as mapping reduction or polynomial reduction.
• noun music An arrangement for a far smaller number of parties, e.g. a keyboard solo based on a full opera.