Meaning

• A solar year, the time it takes the Earth to complete one revolution of the Sun (between 365.24 and 365.26 days depending on the point of reference).

  "we moved to this town a year ago;  I quit smoking exactly one year ago"

• (by extension) The time it takes for any astronomical object (such as a planet, dwarf planet, small Solar System body, or comet) in direct orbit around a star (such as the Sun) to make one revolution around the star.

  "Mars goes around the sun once in a Martian year, or 1.88 Earth years."

• A period between set dates that mark a year, from January 1 to December 31 by the Gregorian calendar, from Tishiri 1 to Elul 29 by the Jewish calendar, and from Muharram 1 to Dhu al-Hijjah 29 or 30 by the Islamic calendar.

  "A normal year has 365 full days, but there are 366 days in a leap year."

• A scheduled part of a calendar year spent in a specific activity.

  "During this school year I have to get up at 6:30 to catch the bus."

• A Julian year, exactly 365.25 days, represented by "a".

• A level or grade in school or college.

  "Every second-year student must select an area of specialization."

• The proportion of a creature's lifespan equivalent to one year of an average human lifespan (see also dog year).

  "Geneticists have created baker's yeast that can live to 800 in yeast years."

Meaning

• A very long time.

  "It took years for the bus to come."