Chris Doyle, from OEDILF, posted this superb limerick (I wish he were here!). What other words only have pairs of letters?

They're arraigning an angel in heaven
Who's charged with purloining the leaven.
(This arraigning has airs
With its five letter-pairs—
Scintillescent is said to have seven.)

Here's his author's note: "Other longer words comprised solely of letter pairs include unprosperousness, esophagographers, happenchance, and shanghaiings."

Would a word like "through" count?

I think the challenge is to come up with long words wherein each letter is represented an even number of times. "Arraigning" has two As, two Rs, two Is, two Gs, two Ns, total ten letters -- and no singletons. Other examples have four of a given letter, still pairable.

I cheated, and wrote a computer program to do the work for me. Here are a couple of results from a smallish dictionary of English, short simple ones (couscous, tutu, etc.) are omitted. Bilabial is a common linguistic term, and mesosome is a biological term.

arraigning
bilabial
horseshoer
intestines
teammate
mesosome
happenchance

These ones have letters which appear in pairs, but some of the pairs are repeated.

senescence
tattletale

These tend to fall into two categories, random mixture of letters, and the center split ones, like teammate, mesosome, happenchance, and horseshoer, where the words are compound, and both halves share the same letters. I can't seem to access my computer with a larger lexicon file, so this one didn't have words like esophagographers.

To pull a Hofstadter - any threesie-words? Foursies?

I found "deeded", and that is the only one I can find of any higher order.

How about words where each letter occurs more than once? This is a larger set than the previous, so let's stick with words where each letter occurs some large amount of times. This appears to be fruitless, as I've only found "deeded". That is, there don't appear to be any other English words where each letter than appears shows up at least 3 times. Unless someone where "de-deeded", of course.

On another note, I found a fun British word, "transistorisation". It doesn't really fit in any of the above categories, but it is fun to look at.

Oddly, "deeded" was mentioned in my newspaper the other day. Somehow the subject of the longest word that could be formed with the least number of different letters came up, and it won with only two.

Wow, those are great! Sean, did you come up with those by yourself? Being a nurse and all, I loved Chris's "esophagographers." I will say, though, that I haven't found it in a dictionary. It makes sense, though; it is the one who takes x-rays of esophaguses (or is it esophagi?).

I wrote a computer program in about 10 minutes. Then I spent 15 minutes tracking down a file which listed most words in the English language. After that, the computer did the work.

I left a couple of common words I found out, for those who want to find some on their own.

A bit of searching lead me to sestettes, a nine letter word with three letters, three times (that makes sense, right?).

Welcome Naed! Another Aussie I see!

Another oddity about "deeded" (mentioned above) is that it is the longest word that can be spelt using just one button on a mobile/cell phone.

Welcome, Naed!

And what a wonderful word! In looking it up it is a synonym for a sextet, right? It also means the last 6 lines of a sonnet?