# Longest Word With *Only* Repeating Character Pairs

Inspired by and Opposite of: Longest Word without repeating character-pairs

The challenge is to find an English word in which every character pair appears at least twice. ("Word" does not include acronyms or proper names. Hyphenated words are included but the hyphen doesn't count as part of a pair.)

Bad word: mama contains the pair ma twice but am only once
Bad word: aa seems clever but still only has the pair once.
Good "word": aaa is not a word but it does contain its only pair aa twice.

Preference will be given to words found on Dictionary.com

Here's a check method in Excel: Input the word in the cell A1 and then input this formula somewhere else as an array formula using Ctrl+Shift+Enter: (TRUE = valid word, FALSE = invalid word)

=(SUM(LEN($A$1)-LEN(SUBSTITUTE(UPPER($A$1),MID(UPPER($A$1),ROW(OFFSET($A$1,0,0,LEN($A$1)-1)),2),"")))/4)+1>=LEN($A$1)


I've been told this javascript function will perform the same check although I haven't used the language in years and can't verify:

function test(e){for(l=[],i=1;i<e.length;i++)p=e[i-1]+e[i],l.push(p);return l2=new Set(l),l.length/l2.size==2?!0:!1}


NOTE: The answers thus far and the scratches I tried to come up with were all of the form [string][same string][first letter of string]. I'd be interested in finding one of a different form although the longest of any form will be accepted as the answer.

• Immediately thought of Bobobo-bo Bo-bobo... – Curmudgeon Jul 6 '15 at 14:49
• muhnuhmuhnuh <shrug> – MackTuesday Jul 6 '15 at 18:11
• @MackTuesday Did you mean muh nuh muh nuh? – Engineer Toast Jul 6 '15 at 18:34
• @EngineerToast Yes. =) – MackTuesday Jul 6 '15 at 19:19
• FYI, your excel formula does not work. I tried it and the only valid string I could find was the empty one. – Conor O'Brien Jul 6 '15 at 20:52

I've found a possible word, though it seems... invalid

11 letters

kinnikinnik
It's on Dictionary.com as kinnikinnick, though it includes the above form in the "Also" section.

• I think that things listed as "also" on Dictionary.com would be considered valid. That indicates that they are accepted spellings. – Engineer Toast Jul 6 '15 at 15:18
• How in the world did you find that!? – JLee Jul 6 '15 at 15:35
• What does it mean? – Jack Aidley Jul 6 '15 at 15:51
• According to Dictionary.com, it is 'a mixture of bark, dried leaves, and sometimes tobacco, formerly smoked by the Indians and pioneers in the Ohio valley.' – Demesne Jul 6 '15 at 16:01
• This is the longest valid word appearing in Ubuntu's american-english-insane dictionary, so I doubt it will be beaten. – Nate Eldredge Jul 6 '15 at 17:13

I think I can do 7 letters:

ALFALFA

Which features the letter pairs:

'AL' twice, 'LF' twice, and 'FA' twice

• Nice! I was sure that there wouldn't be any such words. – Daniel Jul 6 '15 at 19:22
• mark got the tick but you get +1 for a quick and popular answer. – Engineer Toast Jul 7 '15 at 21:44
• anapanapa (9)
• sasararas (9)
• kinnikinnik (11)

These words are the longest I could find. Kudos to the guy who found kinnikinnik first, though. 11 letters is crazy.

• Does "anapanapa" have a meaning? – Tanner Swett Jul 7 '15 at 1:35
• sasararas is nice since it's a not the a word on the form [string][string][first character of string] – Taemyr Jul 8 '15 at 11:33

Here’s another seven letter word:

ENTENTE, which is on Dictionary.com

As with Bailey M’s answer, there are three pairs, each of which appears twice::

EN, NT and TE

I found this by going through the Unix words list with a Python script (Gist).

That threw up a few other words, but I can neither find them on Dictionary.com, nor indeed find any other definition or explanation for why they’re there:

ANAPANAPA (9) – four pairs of two: AN, NA, AP, PA
DEEDEED (7) – three pairs of two: DE, EE, ED

Another 11-letter word is strumstrums, although it doesn't exist at dictionary.com unfortunately.

According to wiktionary the word strumstrum appeared in the 1913 edition of Webster's Dictionary, and refers to a type of musical instrument. The plural is strumstrums.

Here's what I found using the Enable word list:

alfalfa
entente
sarsars
tzitzit

By using the same word list as Golden Dragon and the regular expression

 ([a-zA-Z]{4})\1+
#Match any group of four letters that occurs at least twice in a word


I was able to find

• lavalava
• mahimahi
• beriberi
• caracara
• chowchow
• couscous
• froufrou
• greegree
• guitguit
• kavakava

and hotshots which is of a little higher "quality".

These all have eight letters obviously. It is not so easy, to match words that consist of different repeating groups, though.

• The problem with these is that the letter group in the middle of the world (for instance, 'al' for lavalava) is not matched anywhere else. – Bailey M Jul 6 '15 at 20:16
• BUT if any of them are singular nouns, then putting an "s" on the end (e.g. "beriberis") will make it meet the criteria! I'll undo my downvote if you edit with this fix :-) – Rand al'Thor Jul 6 '15 at 23:12
• @randal'thor I don't think that would fix them unless the first letter of the word is "s" which would make the fifth letter of the word "s" – MisterEman22 Jul 6 '15 at 23:18
• @MisterEman22 Um, yes - good point. That leaves us with things like "caracarac" and "greegreeg", and probably none of those are words :-( – Rand al'Thor Jul 6 '15 at 23:22
• Here is a different regexp that does not work. (.NET flavor for arbitrary length lookaround) ^(?:((?:.){2})(?:(?<=\1.*..)|(?=.*\1)))+\$ – Taemyr Jul 7 '15 at 11:39

Another 11 letter one:

UNKULUNKULU

Not present on dictionary.com unfortunately, but thought it was interesting enough to add here.