\Quan"ti*ty\, v. t. [L. quantus now much + -fy.]
To modify or qualify with respect to quantity; to fix or
express the quantity of; to rate.

\Quan"ti*ty\, n.; pl. {Quantities}. [F. quantite, L.
quantitas, fr. quantus bow great, how much, akin to quam bow,
E. how, who. See {Who}.]
1. 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. Hence, in specific uses:
   (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) (Gram.) 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) (Mus.) The relative duration of a tone.
2. That which can be increased, diminished, or measured;
   especially (Math.), anything to which mathematical
   processes are applicable.
Note: 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,
      viz., 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.
{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} (Mech.), in a body, the relative amount
   of its motion, as measured by its momentum, varying as the
   product of mass and velocity.
{Known quantities} (Math.), quantities whose values are
   given.
{Unknown quantities} (Math.), quantities whose values are
   sought.