# Five-letter English word that contains only two distinct letters

Is there any 5-letter English word that uses only 2 distinct letters?

• Did you make this puzzle? I am pretty sure this site is for puzzles you made only. Are you even sure this exists? – user64742 Jul 17 '16 at 3:09
• @TheGreatDuck - Actually externally sourced puzzles are "fine", although preferably with citation, and preferably not ones that have solutions pasted all over the net, or are just poor quality. There is a tag for unsolved-mysteries, for example. This does not seem to be everywhere or to be of poor quality (or an unsolved mystery of course), although a couple of words for close relations spring to mind pretty quickly (ease != poor quality). – Jonathan Allan Jul 17 '16 at 4:36
• @JonathanAllan true, but a user shouldnt just randomly make something up and expect an answer. From my perspective this seems like a random question. This is a new user and I believe this question is spam. – user64742 Jul 17 '16 at 5:07
• @TheGreatDuck Clearly this is not spam, there is a specific question and no link. You might debate it being off-topic. Also, the user is active on a few other SE sites, so I imagine they thought this would be the correct stack to ask this question on, rather than, say, English.SE and have not just come here to post a "random" question. – Jonathan Allan Jul 17 '16 at 5:24
• @TheGreatDuck: I dunno what counts as "spam" here, but I'm definitely a human being who is very active on various SE sites. I happened to need an answer to this question, and this was the best resource I could think of for getting the question answered (as indeed it proved to be, as I promptly got answers). I seem to have caused great inconvenience and distress by posing this question. So please do accept my sincere apologies. – Kenny LJ Jul 18 '16 at 2:51

This regex dictionary returns 34 matches. I removed the ones that were proper nouns or that I couldn't find definitions of:

ajaja: species name of the roseate spoonbill?
alala: ʻalalā, a Hawaiian crow.
anana: alternate name for a pineapple?
arara: a palm cockatoo.
cocco: a taro tuber.
esses: plural of "ess", the letter S.
hoooo: transliteration of Japanese 鳳凰 (phoenix).
mamma: alternative spelling of "mama", or a mammary gland.
nanna: a word for a grandmother.
pappa: a word for a father.
susus: plural of "susu", a money sharing group.
taata: a word for a father.
tatta: a bamboo frame.
uhhuh: (usually hyphenated) an affirmative response.
ululu: a wail.
unnun: to cause someone to stop being a nun.
xxiii: Roman numerals for 23 (32, 39, 41, etc. weren't listed but would also work the same).

• What's the regex for that? – Carl Jul 17 '16 at 2:48
• Thanks. I think MAMMA is the one word that comes closest to qualifying as an "English word". – Kenny LJ Jul 17 '16 at 3:02
• @Carl ^([a-z])\1*([a-z])(\1|\2)*\$ with the length restricted to 5 produces that list. – f'' Jul 17 '16 at 3:04

Some I can think of are:

ESSES, the plural of ess (the letter S)
MAMMA, "a mammary gland and its accessory parts"