The difference between Expansion and Reduction

Expansion as a noun:

The act or process of expanding.

Expansion as a noun:

The fractional change in unit length per unit length per unit temperature change.

Expansion as a noun:

A new addition.

Expansion as a noun:

A product to be used with a previous product.

Expansion as a noun:

That which is expanded; expanse; extended surface.

Expansion as a noun (steam engines):

The operation of steam in a cylinder after its communication with the boiler has been cut off, by which it continues to exert pressure upon the moving piston.

Reduction as a noun:

The act, process, or result of reducing.

Reduction as a noun:

The amount or rate by which something is reduced, e.g. in price.

Reduction as a noun (chemistry):

A reaction in which electrons are gained and valence is reduced; often by the removal of oxygen or the addition of hydrogen.

Reduction as a noun (cooking):

The process of rapidly boiling a sauce to concentrate it.

Reduction as a noun (mathematics):

The rewriting of an expression into a simpler form.

Reduction as a noun (computability theory):

a transformation of one problem into another problem, such as mapping reduction or polynomial reduction.

Reduction as a noun (music):

An arrangement for a far smaller number of parties, e.g. a keyboard solo based on a full opera.

Reduction as a noun (philosophy, phenomenology):

A philosophical procedure intended to reveal the objects of consciousness as pure phenomena. (See phenomenological reduction.)

Reduction as a noun (medicine):

A medical procedure to restore a fracture or dislocation to the correct alignment.