# cardinality

## cardinality

[kahr-dn-al-i-tee]
noun, plural cardinalities. Mathematics.
(of a set) the cardinal number indicating the number of elements in the set.

Origin:
1930–35; cardinal + -ity

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World English Dictionary
 cardinality (ˌkɑːdɪˈnælɪtɪ) —n 1. maths the property of possessing a cardinal number 2. maths, logic (of a class) the cardinal number associated with the given class. Two classes have the same cardinality if they can be put in one-to-one correspondence

Collins English Dictionary - Complete & Unabridged 10th Edition
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Etymonline
Word Origin & History

cardinality
1520s, "condition of being a cardinal," from cardinal (q.v.) + -ity. Mathematical sense is from 1935.
Online Etymology Dictionary, © 2010 Douglas Harper
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FOLDOC
Computing Dictionary

### cardinality definition

mathematics
The number of elements in a set. If two sets have the same number of elements (i.e. there is a bijection between them) then they have the same cardinality. A cardinality is thus an isomorphism class in the category of sets.
aleph 0 is defined as the cardinality of the first infinite ordinal, omega (the number of natural numbers).
(1995-03-29)

The Free On-line Dictionary of Computing, © Denis Howe 2010 http://foldoc.org
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Example sentences
The cardinality of a finite set is simply the number of members in it.
Since cardinality is such a common concept in mathematics, a variety of names are in use.
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