The phrase is moot point, not mute point. Moot means debatable — and in American usage, of no practical relevance because the matter is settled. Mute means silent. The "mute point" error is common because the phrase is heard far more often than it is read.
The core difference
An adjective about debate and an adjective about silence.
- moot — debatable, or (chiefly US) no longer relevant: a moot point.
- mute — silent: fell mute, the mute button.
The transatlantic split
British usage keeps the older sense: a moot point is one open to debate and worth arguing. American usage has moved to mean the opposite in effect — the question is academic because it no longer matters. So "that's moot" can mean "worth discussing" or "not worth discussing" depending on who is speaking, which is genuinely worth knowing.
Where the word comes from
A moot was an Anglo-Saxon assembly for debate — the same root as meet. Law schools still hold moot courts, where students argue hypothetical cases. That is the original sense preserved intact.
Frequently asked questions
Is it "moot point" or "mute point"?
Moot point. Mute means silent.
Does moot mean debatable or irrelevant?
Both, depending on where you are. British usage keeps "open to debate"; American usage often means academic because the matter is settled.
What is a moot court?
A law-school exercise arguing hypothetical cases — preserving the original sense of moot as a debating assembly.