1. Academic life and interests. Professors, students, tenure, publish or perish, journals and final exams -- all that good stuff.
2. The academic environment.
The word academia comes from the Akademeia in Greece, near Athens. Akademeia was made famous in scholarly circles by Plato's Academy, founded about 385 BC. The word doesn't actually have anything to do with schools and study; Akademia literally means "the grove of Akademos" in Greek. Akademos was a minor Greek hero who helped to rescue Helen of Troy.
Those of us with retarded senses of humor take this as license to call Nethack, Diablo, and especially Super Mario Brothers (who are also rescuing a princess) as academic endeavors. Sorry. Nevermind.
Here are some sample usages, blatantly stolen from random webpages:
"I'm not convinced that academia operates solely on an aggressive exertion of privilege."
"The Village Voice offers a pretty interesting piece on
blogging in academia."
"Not to take anything away from academia and the news
media, but..."