(medicine, smoking) A unit for measuring the number of cigarettes a person has smoked previously; it is calculated by multiplying the average number of packs of cigarettes the person smokes per day by the number of years the person has smoked.

Alternative form of yeargroup

plural of year-group

plural of pack year

plural of pack-year

Alternative spelling of pack-year.

A year in which a certain species or population of plants produces a very large quantity of seeds or fruit.

plural of mast year

Taking place in or relating to the middle of a year.

plural of year-bird