Cardinality may refer to:
Cardinality of a set, a measure of the "number of elements" of a set in mathematics Cardinality of a musical set, the number of pitch classes Cardinality (data modeling), a term in database design, e.g. many-to-many or one-to-many relationships Cardinality (SQL statements), a term used in SQL statements which describes the "uniqueness" of the data in a given column Cardinal utility, in contrast with ordinal utility, in economics