n. a body of students who graduate together; "the class of '97"; "she was in my year at Hoehandle High"

n. the period of time that it takes for a planet (as, e.g., Earth or Mars) to make a complete revolution around the sun; "a Martian year takes 687 of our days"

n. a period of time containing 365 (or 366) days; "she is 4 years old"; "in the year 1920"

n. a period of time occupying a regular part of a calendar year that is used for some particular activity; "a school year"