Rendaku and Linguistics

I’ve got rendaku on the brain and just want to gather data.

Hypothesis: compounds formed with the initial word being an i-adjective consistently do not undergo rendaku.

Background research: In my Japanese Linguistics class, we discussed the possible origin of rendaku arising from compounds initially made with の. For example, (うみ)(かめ) uminokame → uminkame → umigame ウミガメ。 If I can find the paper that first proposed this theory, I will link it here. Other background research: I can’t find papers via Google Scholar that mention i-adjectives being a blocker of rendaku, but I also don’t have access to many full papers and I may be a bit lazy to read through dozens of 30+ papers on rendaku.

Goal: gather compound words made with an initial i-adjective that either do or don’t experience rendaku. I’ll fill and edit a wiki that I intend to make shortly after this and other users are welcome to add words as well. I suspect though that like some of my other language projects on the forums that I might forget about continuing this one. Such is life. So while I would like to make a comprehensive list, please don’t be upset if it’s short.

Notes for editing the list!

  1. Please use the dictionary form of the words
  2. Please arrange the words in the Japanese order aka 五十音

~The Rendaku-less List~

First Word (must be an i-adjective) Second Word (can be anything) Compound Word Kana Reading
(あか) (つち) 赤土(あかつち) あかつち
(あか) (しお) 赤潮(あかしお) あかしお
(あま) (くち) 甘口(あまくち) あまくち
(から) (くち) 辛口(からくち) からくち
(くろ) (かみ) 黒髪(くろかみ) くろかみ
(くろ) () 黒子(くろこ) くろこ
(くろ) 故障(こしょう) 黒故障(くろこしょう) くろこしょう
(はや) (くち) 早口(はやくち) はやくち
(にが) () 苦手(にがて) にがて
(わる) (くち) 悪口(わるくち) わるくち

~The Rendaku List~

  • Note: for this list, it is fine to include i-adjectives that are also nouns without the end い
First Word (must be an i-adjective) Second Word (can be anything) Compound Word Kana Reading
(あお) () 青葉(あおば) あおば
(あお) (そら) 青空(あおぞら) あおぞら
(あお) 写真(しゃしん) 青写真(あおじゃしん) あおじゃしん
(あか) (かみ) 赤髪(あかがみ) あかがみ
(あか) (たま) 赤玉(あかだま) あかだま
(あか) (さけ) 甘酒(あまざけ) あまざけ
(しろ) () 白毛(しろげ) しろげ
() () ()() すいば
(なが) () 長引(ながび) ながびく
(なが) (はなし) 長話(ながばなし) ながばなし
(なが) 風呂(ふろ) 長風呂(ながぶろ) ながぶろ
(なが) (くつ) 長靴(ながぐつ) ながぐつ
(なが) (つくえ) 長机(ながづくえ) ながづくえ
(なが) 太刀(たち) 長太刀 ながだち
(なが) () 長着(ながぎ) ながぎ
(なが) 煙管(きせる) 長煙管 ながぎせる
(わる) (くち) 悪口(わるぐち) わるぐち
(わる) () 悪気(わるぎ) わるぎ
(あま) 噛み(かみ) 甘噛み(あまがみ) あまがみ

There’s also 悪口, which can be わるくち and わるぐち (as well as on’yomi readings, あっこう lol)
You should make a list with exceptions too maybe


赤髪 gets rendaku. Maybe that doesn’t count since 赤 can stand alone outside of 赤い?


Done :slight_smile:
I had meant for the first list to include both, but you’re right that another list would probably be much better.

For both of these, it’s really interesting to note that both of the first words can stand as nouns on their own. I don’t have the level of Japanese yet to do worthwhile etymology, but I would propose that the noun forms of these words existed first and that’s why they experience (sometimes optional) rendaku. Thank you! This helps support my theory and evokes more questions! :smiley:

甘酢 from 甘い + 酢 seems to be an exception

I have zero idea how to format the main post so i’m not going to attempt editing it sorry


Don’t have the time to properly add it into the chart atm, but 甘酒(あまざけ)is the only thing I can think of off the top of my head.

Edit: Added it!


Do you possibly still have the wiki edit open? For some reason it won’t let me edit and keep your addition :c

Those are good examples! I don’t see anything on an initial search to see if あま is a noun on its own, so those could disprove my theory or I might need to do some better etymology

Ugh I’m so sorry, apparently I left it open earlier when double checking it :tired_face: Sorry! It should be fixed now!

Also- As far as I know 甘 is not a noun in and of itself. 甘さ and 甘味 would be, but obviously those are different.

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It still giving me an error <,< Maybe you could try refreshing the page? I think it must be some weird discourse thing.

Yeah, the さ suffix is specifically a nominalizer. While (わる) and (あか) can be explained as using the noun form and therefore following the の→ん→(voicing), あま seems like it might exclusively be an i-adjective.

I’ve been browsing other threads and even closed out the window at one point earlier, so it shouldn’t be on my end anymore if there’s still an error :neutral_face:

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Dang. I’m not sure what’s up with that then.

That’s weird, it let’s me make edits still? Not sure why though.

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(あま)い also produces 甘噛(あまが)み.

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Some additions, but I don’t want to mess with the table in case I mess it up again :joy:

にが苦手にがて (This one feels different though, maybe since it’s not literal?)


I’m struggling to come up with any that aren’t colors or flavors atm. Would be curious to see if anyone else knows any?


It looks like it was maybe just that I needed to refresh the page?? All the edits seem to stick now

Huh, it looks like sui has an interesting story behind it since the い is adopted into the compound reading and it’s also the kanji in ()っぱい. I wonder if that い used to be a ち

colors and flavors seem to be the most common as far as I can tell. I’ll have to remember to add Aoshima when I have the energy to fiddle with it all again.

This makes me feel more and more like it’s likely that あま existed as a word on it’s own at some point and is just archaic now.

Maybe derived from (あま)の? Hahaha just speculating, alttough I’d definitely make a connection between something sweet and heaven.

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Oooooh, nice! I need to improve my Japanese more so I can look into that :eyes:

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The Tofugu people did a research about it a couple years ago. You might find a bunch of more interesting example in there. They also discuss concepts like dvandva or lyman’s law and common mistakes or exceptions. They also linked their sources at the end of the article. Hope it will help you with your research :four_leaf_clover: