The act of reducing, or state of being reduced; as the reduction of a body to powder; the reduction of things to order.

Diminution; as the reduction of the expenses of government; the reduction of the national debt.

Conquest; subjugation; as the reduction of a province to the power of a foreign nation.

In arithmetic, the bringing of numbers of different denominations into one denomination; as the reduction of pounds, ounces, pennyweights and grains to grains, or the reduction of grains to pounds; the reduction of days and hours to minutes, or of minutes to hours and days. The change of numbers of a higher denomination into a lower, as of pounds into pence or farthings, is called reduction descending; the change of numbers of a lower denomination into a higher, as of cents into dimes, dollars or eagles, is called reduction ascending. Hence the rule for bringing sums of different denominations into one denomination, is called reduction.

In algebra, reduction of equations is the clearing of them of all superfluous quantities, bringing them to their lowest terms and separating the known from the unknown, till the unknown quantity alone is found on one side, and the known ones of the other.

Reduction of a figure, menis the making of a copy of itona smaller or larger scale, preserving the form and proportions.

In surgery, the operation of restoring a dislocated or fractured bone to its former place.

In metallurgy, the operation of bringing metallic substances which have been changed, or divested of their metallic form, into their natural and original state of metals. This is called also revivification.