Etymology: Middle English yere, from Old English gēar; akin to Old High German jār year, Greek hōros year, hōra season, hour
Date: before 12th century
a. the period of about 3651/4 solar days required for one revolution of the earth around the sun
b. the time required for the apparent sun to return to an arbitrary fixed or moving reference point in the sky
c. the time in which a planet completes a revolution about the sun <two Mercury years> 2. a. a cycle in the Gregorian calendar of 365 or 366 days divided into 12 months beginning with January and ending with December b. a period of time equal to one year of the Gregorian calendar but beginning at a different time 3. a calendar year specified usually by a number <died in the year 1900> 4. plural a time or era having a special significance <their glory years> 5. a. 12 months that constitute a measure of age or duration <her 21st year> — often used in combination <a year-old child> b. plural age <wise beyond her years>; also the final stage of the normal life span 6. a period of time (as the usually 9-month period in which a school is in session) other than a calendar year
New Collegiate Dictionary. 2001.