a period of 365 or 366 days, in the Gregorian calendar, divided into 12 calendar months, now reckoned as beginning Jan. 1 and ending Dec. 31 (calendar year or civil year). Compare common year, leap year.
2.
a period of approximately the same length in other calendars.
3.
a space of 12 calendar months calculated from any point: This should have been finished a year ago.
4.
Astronomy.
a.
Also called lunar year.a division of time equal to 12 lunar months.
Also called sidereal year.a division of time equal to the equinoctial year plus 20 minutes, representing the time required for the earth to complete one revolution around the sun, measured with relation to the fixed stars. Compare anomalistic year.
5.
the time in which any planet completes a revolution round the sun: the Martian year.
6.
a full round of the seasons.
7.
a period out of every 12 months, devoted to a certain pursuit, activity, or the like: the academic year.
time; period: the years of hardship and frustration.
d.
an unusually long period of time of indefinite length: I haven't spoken to them in years.
9.
a group of students entering school or college, graduating, or expecting to graduate in the same year; class.
—Idioms
10.
a year and a day, a period specified as the limit of time in various legal matters, as in determining a right or a liability, to allow for a full year by any way of counting.
11.
from the year one, for a very long time; as long as anyone remembers: He's been with the company from the year one.
12.
year in and year out, regularly through the years; continually: Year in and year out they went to Florida for the winter. Also, year in, year out.
Origin: bef. 900; ME yeer, OE gēar; c. D jaar, G Jahr, ON ār, Goth jēr, Gk hôros year, hrā season, part of a day, hour
solar year n. The period of time required for the earth to make one complete revolution around the sun, measured from one vernal equinox to the next and equal to 365 days, 5 hours, 48 minutes, 45.51 seconds. Also called astronomical year, tropical year.
[yeer] 
rā season, part of a day, hour