Wikipedia:

Quantity | quantulum

Summary:

a kind of property which exists as magnitude or multitude. It's among the basic classes of things along with quality, substance, change, and relation. Quantity was first introduced as quantum, an entity having quantity. Being a fundamental term, ...  (38 of 1995 words)

Link:

http://en.wikipedia.org/wiki/Quantity  [cite]

Wiktionary:

quantity | quantities [plural]

Summary:

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. | An indefinite amount of something. | A ...  (41 of 320 words, 5 senses, 1 etymology, pronunciation)

Link:

http://en.wiktionary.org/wiki/quantity  [cite]

Merriam-Webster:

quantity | quantities [plural] | qty [abbreviation]

Summary:

an indefinite amount or number | a determinate or estimated amount | total amount or number | a considerable amount or number —often used in plural | ...  (23 of 195 words, 11 senses, 1 etymology, pronunciation)

Link:

http://www.merriam-webster.com/dictionary/quantity  [cite]

Random House:

quantity | quantities [plural] | qty.

Summary:

a particular or indefinite amount of anything. | an exact or specified amount or measure. | a considerable or great amount. | [math] ; the property of ...  (24 of 164 words, 9 senses, pronunciation)

Link:

http://dictionary.infoplease.com/quantity  [cite]

Encarta:

quantity | quantities [plural] | qty. [abbreviation] | be an unknown quantity

Summary:

an amount or number of something | the measurable property of something | a large amount or number | a mathematical entity that has a numerical value ...  (24 of 159 words, 7 senses, 1 etymology, pronunciation)

Link:

http://encarta.msn.com/dictionary 1861697549/definition.html  [cite]

Britannica:

measure

Summary:

in mathematics, generalization of the concepts of length and area to arbitrary sets of points not composed of intervals or rectangles. Abstractly, a ...  (23 of 104 words)

Link:

http://www.britannica.com/EBchecked/topic/371680/measure  [cite]

Columbia:

measure

Summary:

in music, a metrical unit having a given number of beats, the first of which normally is accented, although the accent may be displaced by ...  (25 of 71 words)

Link:

http://www.infoplease.com/ce6/ent/A0832421.html  [cite]