noncardinal

Noncardinal is an adjective formed from non- plus cardinal, used to indicate something that is not cardinal in a given sense. Because cardinality, cardinal directions, and related concepts have different specialized meanings in different fields, noncardinal does not have a single universal definition. In most contexts it serves as a contrast to a specific use of the word cardinal and is understood only within that context.

In mathematics, cardinal numbers measure the size of a set, while ordinal numbers describe order. The term noncardinal is sometimes employed to refer to objects that are not cardinals, such as certain ordinals that are not cardinals. However, most mathematical writers would simply describe such objects as ordinals rather than labeling them noncardinal, since noncardinal is not a standard technical category.

In geography and navigation, cardinal directions refer to the four main compass points: north, south, east, and west. Directions that lie between them, such as northeast, southeast, southwest, and northwest, are typically called intercardinal directions. Some authors may loosely use noncardinal to mean these intermediate directions, but the standard term remains intercardinal.

In linguistics and related language studies, cardinal numerals express quantity (one, two, three), whereas noncardinal numerals may be used in some discussions to refer to non-quantifying or non-cardinal forms, such as ordinals (first, second) or other non-quantity-related numeral types. Usage varies by author and field, and noncardinal is not a universally established technical category.

Overall, noncardinal is a polyvalent term whose meaning depends on context, and it is often a stylistic or transitional label rather than a fixed technical term. See also cardinal, ordinal, intercardinal, cardinal directions.