coefficient

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

• noun A number or symbol multiplied with a variable or an unknown quantity in an algebraic term, as 4 in the term 4x, or x in the term x(a + b).
• noun A numerical measure of a physical or chemical property that is constant for a system under specified conditions, such as the coefficient of friction.

from The Century Dictionary.

• noun Same as coefficient of variation.
• noun Superior lethal coefficient, that medium concentration of a disinfectant which will kill bacteria spores in water at a temperature of 20–25° C. in the shortest time.
• noun The coefficient of change in electrical resistance of a substance with variation of temperature. The temperature coefficient is given by the equation: in which r is the resistance of the substance at the temperature t_o, and r_o, its resistance at 0°.
• Coöperating; acting in union to the same end.
• noun That which unites in action with something else to produce a given effect; that which unites its action with the action of another.
• noun In algebra, a number or other constant placed before and multiplying an unknown quantity or variable or an expression containing such quantities; also, a number multiplying a constant or known quantity expressed algebraically—that is, by the letters a, b, etc.
• noun In physical, a numerical quantity, constant for a given substance, and used to measure some one of its properties: as, the coefficient of expansion of any substance is the amount which the unit of length (surface or volume) expands in passing from 0° to 1° C.

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

• adjective Coöperating; acting together to produce an effect.
• noun That which unites in action with something else to produce the same effect.
• noun (Math.) A number or letter put before a letter or quantity, known or unknown, to show how many times the latter is to be taken.
• noun (Physics) A number, commonly used in computation as a factor, expressing the amount of some change or effect under certain fixed conditions as to temperature, length, volume, etc..
• noun (Math.) a literal coefficient placed arbitrarily in an algebraic expression, the value of the coefficient being afterwards determined by the conditions of the problem.

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

• adjective cooperating
• noun mathematics A constant by which an algebraic term is multiplied.
• noun A number, value or item that serves as a measure of some property or characteristic.

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

• noun a constant number that serves as a measure of some property or characteristic