amplification

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

• noun The act or result of amplifying, enlarging, or extending.
• noun An addition to or expansion of a statement or idea.
• noun A statement with such an addition.
• noun The process of increasing the magnitude of a variable quantity, especially the magnitude of voltage, power, or current, without altering any other quality.
• noun The result of such a process.
• noun Genetics The process by which extra copies of a gene or a DNA sequence are formed.

from The Century Dictionary.

• noun The act of amplifying or enlarging in dimensions; enlargement; extension.
• noun Specifically
• noun In rhetoric, expansion for rhetorical purposes of a narrative, description, argument, or other discourse; a discourse or passage so expanded; an addition made in expanding.
• noun In logic, an increase in the logical depth (comprehension) of a term without any corresponding decrease of breadth (extension), as the expansion of “plane triangle” into “plane triangle having the sum of its angles equal to two right angles,” which is equivalent to it with respect to extension.
• noun In microscopy, increase of the visual area, as distinguished from magnification (which see).

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

• noun The act of amplifying or enlarging in dimensions; enlargement; extension.
• noun (Rhet.) The enlarging of a simple statement by particularity of description, the use of epithets, etc., for rhetorical effect; diffuse narrative or description, or a dilating upon all the particulars of a subject.
• noun The matter by which a statement is amplified.

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

• noun the act, or result of amplifying, enlarging, extending or adding to
• noun physics the act, or result of independently increasing some quantity, especially voltage, power or current
• noun electronics gain
• noun genetics using the polymerase chain reaction (PCR) for isolating and exponentially amplifying a fragment or sequence of DNA
• noun organic chemistry A procedure used in the nomenclature of complex organic compounds in which the superatoms of a basic structure (a phane) are replaced by cyclic structures (amplificants)

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun addition of extra material or illustration or clarifying detail
• noun (electronics) the act of increasing voltage or power or current
• noun the amount of increase in signal power or voltage or current expressed as the ratio of output to input