What is the longest word that starts with a?

This is a bit of a trick question! There's no single "longest word" that starts with "a" because the definition of a word can be a bit loose.

Here are a few things to consider:

* Dictionary vs. Non-Dictionary Words: There are words that are technically recognized in a dictionary, and then there are words that are made up or have a very limited use.

* Proper Nouns: Names (like people, places, or things) can be incredibly long!

Some examples:

* Longest word in the dictionary: "Floccinaucinihilipilification" (29 letters)

* Longest word starting with "a" in the dictionary: "Antidisestablishmentarianism" (28 letters)

* Longest known proper noun: "The longest word in the English language" (38 letters)

So, depending on what you consider a "word," the answer could be different!