quantity

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

• noun A specified or indefinite number or amount.
• noun A considerable amount or number.
• noun An exact amount or number.
• noun The measurable or countable property or aspect of things.
• noun Mathematics Something that serves as the object of an operation.
• noun Linguistics The relative amount of time needed to pronounce a vowel, consonant, or syllable.
• noun The duration of a syllable in quantitative verse.
• noun Logic The exact character of a proposition in reference to its universality, singularity, or particularity.

from The Century Dictionary.

• noun The being so much in measure or extent; technically, the intrinsic mode by virtue of which a thing is more or less than another; a system of relationship by virtue of which one thing is said to be more or less than another; magnitude.
• noun In the concrete, an object regarded as more or less; a quantum; any amount, magnitude, or aggregate, in a concrete sense: as, a quantity of water: sometimes erroneously used to denote that which should be enumerated rather than measured: as, a quantity of people.
• noun A large or considerable amount.
• noun A piece or part, especially a small portion; anything very little or diminutive.
• noun Proportion; correspondent degree.
• noun In anc. orthoëpy, pros., and metrics, the relative time occupied in uttering a vowel or a syllable; that characteristic of a vowel or a syllable by which it is distinguished as long or short; syllabic measure or time; prosodic length.
• noun In logic, that respect in which universal and particular propositions differ. See proposition, and logical quantity, below.
• noun In electricity, the amount of electricity which passes through any section of a circuit in a unit of time: more exactly termed the strength of the current.
• noun Quantity of comprehension or intension, or logical depth, a relative character of a term such that when it is in excess the term has all the predicates of another term, and more besides; or a relative character of a proposition such that when it is in excess the proposition is followed by all the consequents of another proposition, and more besides.
• noun Quantity of science (Aquinas) or of information, a relative character of a concept such that when it is in excess it has all the subjects and predicates of another concept, and more besides, owing to its being in a mind which has more knowledge. Logical quantity is to be distinguished from the quantity of a proposition.
• noun Specifically, same as duration or time-value: said of musical tones or notes.

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

• noun The attribute of being so much, and not more or less; the property of being measurable, or capable of increase and decrease, multiplication and division; greatness; and more concretely, that which answers the question “How much?”; measure in regard to bulk or amount; determinate or comparative dimensions; measure; amount; bulk; extent; size.
• noun (Logic) The extent or extension of a general conception, that is, the number of species or individuals to which it may be applied; also, its content or comprehension, that is, the number of its constituent qualities, attributes, or relations.
• noun (Gram.) The measure of a syllable; that which determines the time in which it is pronounced.
• noun (Mus.) The relative duration of a tone.
• noun That which can be increased, diminished, or measured; especially (Math.), anything to which mathematical processes are applicable.
• noun A determinate or estimated amount; a sum or bulk; a certain portion or part; sometimes, a considerable amount; a large portion, bulk, or sum.
• noun (Law) its time of continuance, or degree of interest, as in fee, for life, or for years.
• noun in a body, its mass, as determined by its weight, or by its momentum under a given velocity.
• noun (Mech.) in a body, the relative amount of its motion, as measured by its momentum, varying as the product of mass and velocity.
• noun (Math.) quantities whose values are given.
• noun (Math.) quantities whose values are sought.

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

• noun A fundamental, generic term used when referring to the measurement (count, amount) of a scalar, vector, number of items or to some other way of denominating the value of a collection or group of items.
• noun An indefinite amount of something.
• noun A specific measured amount.
• noun A considerable measure or amount.
• noun metrology Property of a phenomenon, body, or substance, where the property has a magnitude that can be expressed as number and a reference.
• noun mathematics Indicates that the entire preceding expression is henceforth considered a single object.

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

• noun an adequate or large amount
• noun the concept that something has a magnitude and can be represented in mathematical expressions by a constant or a variable
• noun how much there is or how many there are of something that you can quantify