- using the letter M incorrectly or to an extreme.
This has nothing to do with alliterative tongue-twisters, like reciting “A missing mixture measure” over and over. The OED offers the necessary context for such an obscure word:
In Latin prose composition: the pronunciation of a final m before a word beginning with a vowel, regarded as a fault by grammarians. Also: the placing of a word with a final m before a word with an initial m.
Interesting fact about Latin grammarians: the profession is not some continuation of Ancient Rome; they only came to exist after the civilization’s collapse. Thus, there is no actual authority on how to pronounce the language, only reasonable arguments that are hashed-out ad infinitum . Think about it: from California to Bangalore people read and write grammatically near-exact English, yet the spectrum of pronunciation and orality is as diverse as Kew Gardens. No one can see the word “Ladder” and figure folks in Chicago say “Lehteh” or that the correct way to say “water” in Philadelphia is “wüdder.”
This is why some words die.