The Greek word for "year", "yearling (calf)", the latter also reflected in Latin vitulus "bull calf", English wether "ram" (Old English weðer, Gothic wiþrus "lamb").In some languages, it is common to count years by referencing to one season, as in "summers", or "winters", or "harvests".As 218 out of every 900 years are leap years, the average (mean) length of this Julian year is A calendar era assigns a cardinal number to each sequential year, using a reference point in the past as the beginning of the era.Worldwide, the most commonly used calendar era is referenced from the traditional—now believed incorrect—year of the birth of Jesus.
In astronomy, the Julian year is a unit of time; it is defined as 365.25 days of exactly The word "year" is also used for periods loosely associated with, but not identical to, the calendar or astronomical year, such as the seasonal year, the fiscal year, the academic year, etc.
Both *yeh₁-ro- and *h₂et-no- are based on verbal roots expressing movement, *h₁ey- and *h₂et- respectively, both meaning "to go" generally (compare Vedic Sanskrit éti "goes", atasi "thou goest, wanderest").
Derived from Latin annus are a number of English words, such as annual, annuity, anniversary, etc.; per annum means "each year", anno Domini means "in the year of the Lord".
Similarly, "year" can mean the orbital period of any planet: for example, a Martian year or a Venusian year are examples of the time a planet takes to transit one complete orbit.
The term can also be used in reference to any long period or cycle, such as the Great Year.
A calendar year is an approximation of the number of days of the Earth's orbital period as counted in a given calendar.