A Season

1. Each of the four divisions of a year: spring, summer, autumn (fall) and winter
2. A part of a year when something particular happens
3. A period of the year in which a place is most busy or frequented for business, amusement, etc.
4. (obsolete) That which gives relish; seasoning.
5. (cricket) The period over which a series of Test matches are played.
6. (Canada, US, broadcasting) A group of episodes of a television or radio program broadcast in regular intervals with a long break between each group, usually with one year between the beginning of each.
7. (archaic) An extended, undefined period of time.
8. (video games) The full set of downloadable content for a game, which can be purchased with a season pass.
9. (video games) A fixed period of time in a massively multiplayer online game in which new content (themes, rules, modes, etc.) becomes available, sometimes replacing earlier content

Usage notes

In British English, a year-long group of episodes of a television or radio show is called a series, whereas in North American English the word series is a synonym of program or show.