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the act of or the state of being .
the amount by which something is or diminished.
a form produced by ; a copy on a smaller scale.
cell biology. meiosis, especially the first meiotic cell division in which the chromosome number is by half.
chemistry. the process or result of .
movies. the process of making a print of a narrower gauge from a print of a wider gauge:
the reduction of 35-mm films to 16-mm for the school market.
a village or settlement of indians in south america established and governed by spanish jesuit missionaries.
contemporary examples

it cannot be the case that the reduction of american forces is a strategy for reaching the goal of defeating al qaeda.
obama’s overview of afghanistan war fails to specify goals stephen l. carter december 16, 2010

even with a 15 percent reduction in time for good behavior, such a sentence would allow madoff to get out of jail at 106.
feds want 150 years for bernie allan dodds frank june 25, 2009

enernoc proudly keeps a running ticker of carbon emissions saved through its reduction and efficiency work with customers.
enernoc helps keeps lights on during heat waves through demand response edward ferguson july 19, 2013

but the reduction of books and their contents to mere “information” helps ill-strate the risk of the method.
where’s the bailout for publishing? stephen l. carter march 16, 2009

but there is nothing—zero, zilch, nada—in the ryan plan that demonstrates how that reduction would come to p-ss.
ryan budget plan sounds good but lacks substance zachary karabell august 12, 2012

historical examples

there will be no surplus for the reduction of debt, or to meet new demands.
rebuilding britain alfred hopkinson

the first operation to be taken up is the reduction of prints which are too dark.
bromide printing and enlarging john a. tennant

i cannot make this reduction as large as i should have done, if i had more satisfactory accounts of the intentions of prussia.
lord lyons: a record of british diplomacy thomas wodehouse legh newton

if the tray be rocked gently the reduction will be quite uniform.
bromide printing and enlarging john a. tennant

for circular tours, the companies make a reduction of 25 per cent on the regular fare.
direct legislation by the citizenship through the initiative and referendum james w. sullivan

noun
the act or process or an instance of reducing
the state or condition of being reduced
the amount by which something is reduced
a form of an original resulting from a reducing process, such as a copy on a smaller scale
a simplified form, such as an orchestral score arranged for piano
(maths)

the process of converting a fraction into its decimal form
the process of dividing out the common factors in the numerator and denominator of a fraction; cancellation

n.

early 15c., “a restoring to a former state; a subjugation” (of a people, etc.), from middle french reducion (13c., modern french réduction) and directly from latin reductionem (nominative reductio) “a leading back, restoration,” noun of action from past participle stem of reducere (see reduce). meaning “diminution, a lessening” is from 1670s; chemical sense of “reversion to a simpler form” is from 1660s.

reduction re·duc·tion (rĭ-dŭk’shən)
n.

the act, process, or result of reducing.

the amount by which something is lessened or diminished.

restoration of an injured or dislocated part to its normal anatomical relation by surgery or manipulation. also called repositioning.

the first meiotic division, in which the chromosome number is reduced. also called reduction division, reduction of chromosomes.

a decrease in positive valence or an increase in negative valence by the gaining of electrons.

a reaction in which hydrogen is combined with a compound.

a reaction in which oxygen is removed from a compound.

re·duc’tion·al adj.
reduction
(rĭ-dŭk’shən)

the changing of a fraction into a simpler form, especially by dividing the numerator and denominator by a common factor. for example, the fraction 8/12 can be reduced to 4/6 , which can be further reduced to 2/3 , in each case by dividing both the numerator and denominator by 2.

a chemical reaction in which an atom or ion gains electrons, thus undergoing a decrease in valence. if an iron atom having a valence of +3 gains an electron, the valence decreases to +2. compare oxidation.

our living language : beginning students of chemistry are understandably puzzled by the term reduction: shouldn’t a reduced atom or ion be one that loses electrons rather than gains them? the reason for the apparent contradiction comes from the early days of chemistry, where reduction and its counterpart, oxidation, were terms invented to describe reactions in which one substance lost an oxygen atom and the other substance gained it. in a reaction such as that between two molecules of hydrogen (2h2) and one of oxygen (o2) combining to produce two molecules of water (2h2o), the hydrogen atoms have gained oxygen atoms and were said to have become “oxidized,” while the oxygen atoms have (as it were) lost them by attaching themselves to the hydrogens, and were said to have become “reduced.” importantly, though, in the process of gaining an oxygen atom, the hydrogen atoms have had to give up their electrons and share them with the oxygen atoms, while the oxygen atoms have gained electrons. thus comes the apparent paradox that the “reduced” oxygen has in fact gained something, namely electrons. today the terms oxidation and reduction are used of any reaction, not just one involving oxygen, where electrons are (respectively) lost or gained.

any chemical reaction in which the atoms in a material take on electrons.

note: reduction is the opposite of oxidation.

(or “contraction”) the process of transforming an expression according to certain reduction rules. the most important forms are beta reduction (application of a lambda abstraction to one or more argument expressions) and delta reduction (application of a mathematical function to the required number of arguments).
an evaluation strategy (or reduction strategy), determines which part of an expression (which redex) to reduce first. there are many such strategies.
see graph reduction, string reduction, normal order reduction, applicative order reduction, parallel reduction, alpha conversion, beta conversion, delta conversion, eta conversion.
(1995-02-21)