Cardinality (data modeling) definition

Cardinality (data modeling)

WordNet

(1) (mathematics) the number of elements in a set or group (considered as a property of that grouping)

WiktionaryText

Of a set, the number of elements it contains.

The empty set has a cardinality of zero.
The property of a relationship between a database table and another one, specifying whether it is one-to-one, one-to-many, many-to-one, or many-to-many.