What is the longest word starting with letter m?

This is a bit of a trick question! There's no single "longest word" starting with "m" because it depends on what we consider a "word".

Here's why:

* Dictionary Definitions: If we're talking about words in a standard dictionary, there are many contenders for the longest word starting with "m". Some examples include:

* "Microphotomicrography" (23 letters)

* "Malapropos" (11 letters)

* "Microorganism" (13 letters)

* Technical Terms: If we allow for technical terms or scientific names, there are even longer words.

* "Metachromatic leukodystrophy" (25 letters)

* Made-up Words: Technically, we can always create even longer words starting with "m" by combining existing words or using prefixes and suffixes.

So, without a specific dictionary or context, there's no definitive answer to the question!