Definition of: year

(yir) noun
1. The period of time in which the earth completes a revolution around the sun: about 365 days, used as a unit of time, and divided into 12 months. It is now reckoned as beginning January 1 and ending December 31.
2. Any period of 12 months.
3. The period of time during which a planet revolves around the sun.
4. plural Length or time of life; age; sometimes, old age: active for his years.
—astronomical year The period between two passages of the sun through the same equinox, which determines the changing seasons. Its length is 365 days, 5 hours, 48 minutes, 46 seconds. Also equinoctial, natural, solar, or tropical year.
—calendar, civil, or legal year The period of time from midnight of December 31 to the same hour twelve months thereafter. Formerly, in England, the legal year began with March 25, but historic years were counted from January 1. In 1751 the English Parliament prescribed that the legal year should begin with the first of January, 1752.
—common year That of 365 days, approaching most nearly in the number of days to the astronomical year. The leap year has 366 days.
—fiscal year A financial year of a national treasury or of a business at the end of which accounts are balanced; any twelve–month period used as a basis of business reckoning.
—lunar year That of thirteen months, one month being added at intervals to make the mean length of the astronomical year, as in the Hebrew calendar.
—sidereal year The period of 365 days, 6 hours, 9 minutes, 9 seconds, in which the sun apparently returns to the same position among the stars. It is longer than the astronomical year, owing to the precession of the equinoxes.
—Sothic year The fixed solar year of the Egyptians, consisting of 365 days and 6 hours: so called because determined by the heliacal rising of the Dog Star (Sothis). [OE gēar]