Regnal year

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Regnal year" – news · newspapers · books · scholar · JSTOR (January 2007) (Learn how and when to remove this template message)

A regnal year is a year of the reign of a sovereign, from the Latin regnum meaning kingdom, rule. Regnal years considered the date as an ordinal, not a cardinal number. For example, a monarch could have a first year of rule, a second year of rule, a third year of rule, and so on, but not a zeroth year of rule.

Applying this ancient epoch system to modern calculations of time, which include zero, is what led to the debate over when the third millennium began. Regnal years are "finite era names", contrary to "infinite era names" such as Christian era, Jimmu era, Juche era, and so on.