concentration

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

• noun The act or process of concentrating, especially the fixing of close, undivided attention.
• noun The condition of being concentrated.
• noun Something that has been concentrated.
• noun Chemistry The amount of a specified substance in a unit amount of another substance.

from The Century Dictionary.

• noun The act of concentrating.
• noun The act of collecting or combining into or about a central point; the act of directing or applying to one object; the state of being brought from several or all directions to a common point or center, or into one mass or group: as, the concentration of troops in one place; the concentration of one's energies.
• noun Specifically, the voluntary continuous direction of thought upon an object; close attention.
• noun In chem., the act of increasing the strength of fluids by volatilizing part of their water. The matter to be concentrated must, therefore, be less readily evaporated than water, as sulphuric and phosphoric acids, solutions of alkalis, etc.
• noun In metallurgy, the separation of the metalliferous and valuable portions of the contents of a vein, or mineral deposit of any kind, from the gangue. Bringing the ore into the proper condition of purity for the smelter is generally called dressing, but sometimes the word concentration is used in this sense.
• noun In dynamics, the excess of the value of any quantity at any point in space over its mean value within an infinitesimal sphere described about that point as a center, this excess being divided by one tenth of the square of the radius of the sphere. This is the same as the negative of the result of operating with Laplace's operator upon the quantity. The concentration of the potential of gravity is proportional to the density of the gravitating matter at the point considered.
• noun In biology, specifically, the tendency in descendants to-ward the inheritance of characters at earlier stages of growth than those in which such characters first made their appearance in the ancestors of any given series.
• noun Concentration may be: The reduction of volume by the process of concentrating, as by the evaporation of water from a solution, or the removal of gangue from an ore.
• noun The strength of a solution as increased by concentrating it and as depending on the amount of some dissolved substance contained in a given volume of the solution.
• noun The strength of a solution as depending on the amount of some substance dissolved in a given amount of the solution, simply, and without reference to any process of concentrating it: it may be measured in percentage, or by specific gravity of the solution.
• noun The number of gram-atoms or gram-equivalents or gram-molecules of the dissolved substance, as the case may be, which are contained in unit volume of the solution. The unit volume is commonly the liter, but sometimes the cubic centimeter. A solution containing one gram-molecule, etc., in the liter is called a normal solution; and one containing one tenth of a grammolecule, etc., in the liter is called a decinormal solution, often written 0.1 normal, or solution.
• noun The number of gram-atoms, gram-equivalents, etc., contained in the unit volume, although not in solution, as in case of gases or vapors. In Herbart's pedagogic system, same as absorption 2.

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

• noun The act or process of concentrating; the process of becoming concentrated, or the state of being concentrated; concentration.
• noun The act or process of reducing the volume of a liquid, as by evaporation.
• noun (Metal.) The act or process of removing the dress of ore and of reducing the valuable part to smaller compass, as by currents of air or water.

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

• noun The proportion of a substance in a mixture.
• noun The act, process or ability of concentrating; the process of becoming concentrated, or the state of being concentrated.
• noun A field or course of study on which one focuses, especially as a student in a college or university.

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

• noun complete attention; intense mental effort
• noun strengthening the concentration (as of a solute in a mixture) by removing diluting material
• noun great and constant diligence and attention
• noun the strength of a solution; number of molecules of a substance in a given volume
• noun increase in density
• noun the spatial property of being crowded together
• noun bringing together military forces