The answer to the question “what is a moot point?” depends on where one is. This term actually has two contradictory meanings which occurred as a result of confusion and language shifts. One meaning, seen in British English, is a point which is debatable and which can be decided through discussion. The other meaning, in United States English, is that of a point which is purely academic in nature, and while it can be discussed, it is not considered worthy of discussing because the discussion will not result in a significant outcome.
The origins of the moot point lie in England, where assemblies were known as moots. A point brought before the moot was an issue which the moot needed to hear, discuss, and decide upon. Moot points, in other words, were issues which needed to be aired in public and judged by an assembly. Such points could theoretically be resolved through discussion.
However, in the United States, the meaning of this word began to shift. This is believed to have occurred as a result of the mock trials held by law students as part of their legal education. Known as moots, these trials provide students with chances to make arguments in a trial environment. These hypothetical arguments had no real world outcome because the trials were not held to decide a matter, and people in the United States began using the term “moot point” in reference to a debate which is academic in nature.
The term further shifted to refer to a point which had no real meaning and thus did not need to be brought up at all. In this sense, for example, someone could say “the discussion about which album to play is a moot point, since the record player is broken.” The law in the United States also has a concept of “mootness,” referring to whether or not a legal matter is worth trying in court. If it is beyond the law, it may be deemed moot, and not brought to court.
Curiously, a variation of this phrase in which “mute” is substituted for “moot” has cropped up in some regions of the world. This usage is wrong, but reflects the shifts which happen as words become archaic. Since “moot” is only familiar to many people in the sense of a moot point, some people have substituted “mute,” a more familiar word in common usage which sounds like it might belong in this phrase. Over time, this usage may become so widespread that it is accepted as proper.