Moot is a word that has shifted meanings over time, which sometimes causes confusion.

Originally, moot meant something worth debating or discussing. In medieval England, a moot was a gathering where people argued about important questions. This meaning survives in law schools today, where students practice arguing cases in “moot court,” pretending to be lawyers presenting different sides of legal questions.

In modern American usage, however, moot usually means the opposite: a question that no longer matters because circumstances have changed. If you're debating whether to bring an umbrella and then the rain stops, the question becomes moot. If two students argue about which movie to see Friday night, but then both get sick and can't go, their debate is moot.

Think of it this way: when something is moot in the modern sense, discussing it further is pointless because the issue has been settled by events. Your teacher might say “That's a moot point” when someone brings up a question that events have already answered.

This creates an interesting problem: when someone says a point is moot, you might need to figure out from context whether they mean it's worth debating or no longer worth debating. In most everyday American conversation, they probably mean it doesn't matter anymore.