nonnumber

Nonnumber is a general term used to describe any value, symbol, or object that is not a numeric quantity within a given system. It is not a formal mathematical term, but it appears in discussions of data types, computing, and pedagogy to distinguish numeric content from nonnumeric content.

In mathematics and logic, nonnumbers can include symbolic objects (such as variables without assigned values), qualitative descriptors, or any elements outside the intended set of numbers. In education, instructors often distinguish numbers from nonnumbers to help students classify quantities, measurements, and data that do not represent numerical amounts.

In computing, the term is commonly linked to Not a Number, abbreviated NaN, which denotes an undefined or unrepresentable numeric result in floating-point arithmetic. Many programming languages treat NaN as a special nonnumeric value, with distinctive behavior in comparisons (for example, NaN is not equal to itself). Nonnumeric data types, such as strings, booleans, dates, or complex records, are stored and manipulated separately from numeric types.

In data analysis and databases, separating numeric from nonnumeric fields supports validation, sorting, and the application of mathematical operations. Nonnumbers may label categories, identifiers, or qualitative attributes rather than quantities, and are essential for representing real-world data that cannot be reduced to numbers.

Etymology: nonnumber is a constructive compound formed from the prefix non- meaning not and the word number.

See also: Not a Number, numeric data type, non-numeric.