tunnusluvun

Tunnusluku is a Finnish noun formed from tunnus, meaning identifier or sign, and luku, meaning number. The genitive singular form is tunnusluvun. The term is used in two broad senses depending on context.

In everyday and digital contexts, tunnusluku commonly refers to an identification or authentication code, such as a personal identification number (PIN) or security code used to access services. These codes are intended to be kept secret and may be numeric or alphanumeric, depending on the system. In ordinary language, tunnusluku is often understood as the code a user enters to verify their identity, for example when using online banking, mobile apps, or other secure services.

In statistics and economics, tunnusluku denotes a numerical indicator or metric used to describe characteristics of data or performance. Examples include growth rates, ratios, and index values. In this sense, the plural tunnusluvut is common when listing multiple indicators that summarize conditions or outcomes.

Morphology and usage notes: the base form is tunnusluku; the genitive singular is tunnusluvun; the plural nominative is tunnusluvut; the plural genitive is tunnuslukujen. The word is a productive compound, and its meaning is clarified by context: security discussions favor the identification/authentication sense, while analytical writing favors the statistical indicator sense.

See also: PIN-koodi, henkilötunnus, salasana. The term is versatile, so careful attention to context is essential to determine which sense of tunnusluku is intended.