A notable event which marks the beginning of such a period.
A geochronologic unit of hundreds of thousands to millions of years; a subdivision of a period, and subdivided into ages (or sometimes subepochs).
A specific instant in time, chosen as the point of reference or zero value of a system that involves identifying instants of time.
A particular period of history, or of a person's life, especially one considered noteworthy or remarkable.
One complete presentation of the training data set to an iterative machine learning algorithm.
To divide (data) into segments by time period.
A scheduled part of a calendar year spent in a specific activity.
A Julian year, exactly 365.25 days, represented by "a".
The proportion of a creature's lifespan equivalent to one year of an average human lifespan (see also dog year).
A period between set dates that mark a year, from January 1 to December 31 by the Gregorian calendar, from Tishiri 1 to Elul 29 by the Jewish calendar, and from Muharram 1 to Dhu al-Hijjah 29 or 30 by the Islamic calendar.
A level or grade in school or college.
A solar year, the time it takes the Earth to complete one revolution of the Sun (between 365.24 and 365.26 days depending on the point of reference).
The time it takes for any astronomical object (such as a planet, dwarf planet, small Solar System body, or comet) in direct orbit around a star (such as the Sun) to make one revolution around the star.