year that does not exist in the Anno Domini / Common Era year-numbering system
"Year zero" is a year that doesn't exist in our standard calendar system—after 1 BC comes 1 AD directly, with no year zero in between. Some people and systems have proposed adding a year zero to make the numbering system more logical and easier to use in calculations, though it remains unused in official timekeeping.
AI-generated from the Wikipedia summary — may contain errors.
A year zero is a date where the current year for a given calendar system is zero. In systems which include a year zero, this year would be the epoch. Year zero does not exist in the Anno Domini (AD) calendar year system commonly used to number years in the Gregorian calendar and Julian calendar. Instead, AD 1 is treated as the epoch, so that the year 1 BC is followed directly by year AD 1. However, there is a year zero in both the astronomical year numbering system (where it coincides with the Julian year 1 BC), and the ISO 8601:2004 system, a data interchange standard for certain time and calendar information (where year zero coincides with the Gregorian year 1 BC; Conversion). There is also a year zero in most Buddhist and Hindu calendars.
History
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).