"Tenure commonly refers to
life tenure in a job and specifically to a senior
academic's
contractual right not to have their position terminated without just cause. (wikipedia)."
In other words, the
academic (professor) has been there so long that basically no matter what he does, they can't fire him. This, in my opinion, leads to laziness and narcissism which can, in turn, lead to you getting a prof. who thinks he is king and doesn't really care about his teaching. Not always, but it's common. It's extremely difficult, if not nearly impossible to fire a tenured professor. It is supposedly meant to foster academic freedom without fear of retribution from the school or community. Whatever.