# Longest Word without repeating character-pairs

What's the longest English word that doesn't contain the same two letters in a row more than once?

Good word : too contains to once and oo once.

Good word : tot contains to once and ot once.

Bad word : aardvark contains most pairs once but ar appears twice.

Handy JavaScript test function :

function test_word(w){
for(var l=[],i=1; i<w.length; i++){
var p=w[i-1]+w[i];
if( l[p] ) return p;
l[p]=true;
}
return true;
}


To test your word read the link above then copy and paste the test function hit enter then use the command:

test_word('yourword');


It will return true if it is good and the repeated characters otherwise.

You can also check the word in Excel by entering the word into the cell A1 and entering this formula elsewhere as an array formula using Ctrl+Shift+Enter: (It will return TRUE if it is good and FALSE if it is not.)

=MAX(LEN($A$1)-LEN(SUBSTITUTE(UPPER($A$1),MID(UPPER($A$1),ROW(OFFSET($A$1,0,0,LEN($A$1)-1)),2),"")))<=2

• Eurgh, programming! :-s – Rand al'Thor Jul 6 '15 at 12:19
• Automated checking of results. Its very useful. – Bob Jul 6 '15 at 12:23
• So the upper limit would be $325$ because ${26 \choose 2}=325$ except that the pairs can interact so the actual limit is lower. Anybody with the math skills to compute it? – Engineer Toast Jul 6 '15 at 12:29
• How about the classic answer of smiles because there's a mile between the first and last letter? – Engineer Toast Jul 6 '15 at 12:35
• @f'' Ah, right. Thanks. I... I don't think we'll find a valid word that long, though. – Engineer Toast Jul 6 '15 at 12:55

A 22-letter word:

counterrevolutionaries!

• This one is noteworthy for being the longest word (so far) that isn't some crazy science/medical term. – Kevin Jul 6 '15 at 12:53
• @Kevin And indeed the only one other than my "incomprehensibility" and some of Demesne's shorter words! – Rand al'Thor Jul 6 '15 at 12:55

A 27-letter word:

psychoneuroendocrinological

A 26-letter word:

A 25-letter word, thanks to Kevin:

immunoelectrophoretically

And now for some words that are shorter than 20 letters, but are still pretty good.

An 18 letter-word:

Arachibutyrophobia (a fear of peanut butter sticking to the roof of one's mouth) - wonder if anyone really suffers from this one..

A 17-letter word:

Quattuordecillion (a cardinal number represented by 1 followed by 45 zeros)

Two 16-letter words:

Slubberdegullion (A filthy, slobbering person); hypervitaminosis (refers to a condition of abnormally high storage levels of vitamins)

A 14-letter word:

phantasmagoria - a sequence of real or imaginary images like those seen in a dream.

• Fan-tastic! But shouldn't it be "phantasmagoria", which is only 14 letters? I've never seen "phanstasmagoria". – Rand al'Thor Jul 6 '15 at 12:51
• @rand Oops, thanks for pointing that out. A typo, my bad. Changed. – Demesne Jul 6 '15 at 12:54

First candidate:

incomprehensibility (19 letters).

Anything longer than that will probably be one of those 'silly' super-long words like floccinaucinihilipification or supercalifragilisticexpialidocious (neither of which work, by the way).

• good tagging edits! – Bob Jul 6 '15 at 12:01
• What's wrong with floccinaucinihilipilification?! (And why doesn't my phone keypad have an interrobang?!) – Ben Jul 6 '15 at 17:43
• @Ben It has "in" twice. – Rand al'Thor Jul 6 '15 at 19:47
• @Ben it is a rotten shame that the interrobang is not on your phone keypad nor on any standard keyboard (to my knowledge). – Conor O'Brien Jul 6 '15 at 20:34

A 20-letter word:

electroencephalogram

immunoelectrophoretically

• NB. I picked this out of the Words With Friends word list. I wonder why it's in there when it can't fit on the board. – Kevin Jul 6 '15 at 12:28
• Interesting that they didn't even bother removing words of length 17+. Bit of a silly choice, isn't it? Out of curiosity, how did you get access to that word list? – Curmudgeon Jul 6 '15 at 12:43
• Unfortunately, I have forgotten how I originally came upon this list. You can download the ENABLE word list, which the WWF list is based on, but it's missing the additions the devs made, like "zen" and "texting". – Kevin Jul 6 '15 at 12:52

24 letters

intercomprehensibilities

A 20-letter word!:

uncharacteristically

And another 22-letter word: deinstitutionalization (Sorry, I messed up on the program. Here is the revised):

def test(w):
l = set()
for i in range(1,len(w)):
p = w[i-1]+w[i]
l2 = l&l
if l2==l:
return False
return True


Here is the code I used to look through a massive amount of words:

f = open("5desk.txt","r") # best match: 5desk.txt

longest = ""

for line in f:
lt = test(line)
line = line.replace("=","").replace("^","").replace("+","").replace("#","")
if(lt):
#print(line,len(line))
if(len(line)>=len(longest) and not (line.find(" ")+1) and not (line.find(",")+1)):
longest = line
print(line,len(line)-1)

print("done.")
input("")


And here is the amalgamated input, proving that rand al'thor has the longest recognized word in my lists:

2+2GFREQ.txt
============
the
3
and
3
for
3
that
4
this
4
from
4
have
4
with
4
your
4
5
information
11
application
11
description
11
development
11
association
11
communication
13
accommodation
13
14
recommendation
14
transportation
14
14
characteristic
14
implementation
14
infrastructure
14
classification
14
discrimination
14
interpretation
14
organizational
14
pharmaceutical
14
rehabilitation
14
telecommunication
17
commercialization
17
multidisciplinary
17
industrialization
17
interrelationship
17
superconductivity
17
videoconferencing
17
counterproductive
17
electrocardiogram
17
misinterpretation
17
counterinsurgency
17
decriminalization
17
electrocardiography
19
compartmentalization
20
counterrevolutionary
20
electroencephalogram
20
2+2LEMMA.txt
============
compartmentalization
20
counterrevolutionary
20
electroencephalogram
20
2OF4BRIF.txt
============
electroencephalogram
20
electroencephalograms
21
2OF12.txt
=========
meter-kilogram-second
21
2OF12INF.txt
============
compartmentalizations
21
counterrevolutionaries
22
3ESL.txt
========
5DESK.txt
=========
6OF12.txt
=========
AGID.txt
========
NEOL2007.txt
============
done.


So until I find another list of words, I believe rand al'thor has the longest word. (Though, on the bright side, I have a nice, long list of runner-ups :P)

• Nice summary. +1, even though I usually don't like programming answers :-) – Rand al'Thor Jul 7 '15 at 17:23

Not the longest one, but I think it deserves a mention in a question like this :)
At 18 letters...

sesquipedalianisms - The practice of using long, sometimes obscure, words in speech or writing