Webster's Revised Unabridged Dictionary · 1913

Quantity

Quantity , noun

[French quantite, Latin quantitas, from quantus bow great, how much, akin to quam bow, English how, who. See Who.]

1.
(Logic) 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.
(a)
(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.
(b)
(Logic) The measure of a syllable; that which determines the time in which it is pronounced; as, the long or short quantity of a vowel or syllable.
(c)
(Logic) The relative duration of a tone.
2.
(Mathematics) That which can be increased, diminished, or measured; especially (Mathematics), anything to which mathematical processes are applicable.

Quantity is discrete when it is applied to separate objects, as in number; continuous, when the parts are connected, either in succession, as in time, motion, etc., or in extension, as by the dimensions of space, namely, length, breadth, and thickness.

3.
A determinate or estimated amount; a sum or bulk; a certain portion or part; sometimes, a considerable amount; a large portion, bulk, or sum; as, a medicine taken in quantities, that is, in large quantities.
The quantity of extensive and curious information which he had picked up during many months of desultory, but not unprofitable, study. — Macaulay
Collocations (5)
Quantity of estate (Law) , its time of continuance, or degree of interest, as in fee, for life, or for years. — Wharton (Law Dict. )
Quantity of matter , in a body, its mass, as determined by its weight, or by its momentum under a given velocity.
Quantity of motion (Mechanics) , in a body, the relative amount of its motion, as measured by its momentum, varying as the product of mass and velocity.
Known quantities (Mathematics) , quantities whose values are given.
Unknown quantities (Mathematics) , quantities whose values are sought.