What's up with compound words that contain two different kanji with the same meaning?

I’m a big etymology nerd, and I’d love to get to the bottom of this. How come, that in some compound words two different kanji are used with the same meaning? Here are a few examples of what I mean:

森林 means forest, but 森 and 林 could also mean forest seperately.
睡眠 means sleep, but 睡 and 眠 could also mean sleep.
中央 means center, but 中 and 央 could also mean center.

I’m sure there are a lot more examples, these are just what came to me at the top of my head. Do you guys have any ideas? ありがとうございます :smiling_face_with_three_hearts:


理由 :eyes:
(apparently minimum character limits are a thing).


Yeah, I was quite surprised by it when I discovered it too :sweat_smile:


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@Jonapedia I don’t think this thread could suit you more :wink:

I’d try and answer it if it weren’t for the fact that I don’t know the answer nor the etymology :sweat_smile:


i have no idea, but maybe it got confusing? with two kanji instead of one, then its more obvious to what the word is. Otherwise, if there was only one of the kanji, and then another different kanji after it, you might think that those two make one word, but they were supposed to be separate words (if that made any sense). But I haven’t seen much Japanese in like the real world so its just a hunch.

睡眠 is a word but 睡 or 眠 is not.

中央 and 中 have different nuances. 央 isn’t really used alone.

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Another example of this is 妊娠 (pregnancy+pregnancy=pregnancy), AFAIK those kanji aren’t used on their own in Japanese


Like morte said, there is no answer because the question itself makes an incorrect assumption. Those all don’t have the same meaning.

Two important things to remember:

  1. Just because an english dictionary or wk tells you a kanji means something, doesn’t necessarily mean it actually means that thing on its own.

  2. When you get your meanings in a single english word, a lot of meaning and nuance can be lost.

I know you said you like etymology so I wish the answer had something more to do with that, but really it doesn’t. Not in these cases at least.

There has been some past discussion about the differences between 林 森 森林 specifically, and I’ll try to find that for you.

EDIT: Here you go. And in this thread I link to an even more in depth discussion


‘Love’ appeared this level for me and after ‘feeling’ in previous level there are so many compound kanji with same meaning love and feeling lol

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Hi. Thanks. I actually passed it by earlier, but I wasn’t sure if I could answer because I’m not sure if the origins of these words are easy to trace. As for why…

I think we could still examine this etymologically by trying to figure out why words with similar (but not identical) meanings and nuances get grouped together, but I don’t think there’s an obvious answer, and in my opinion, it’s also very hard to research because kanji combine with each other in so many different ways, and there are probably new combinations being made right now in order to qualify some new idea. However,

I’d say (at least, as far as Chinese is concerned) that this is half of the issue with relying on dictionary definitions: indeed, some kanji rarely function alone, even in Chinese, where this is possible. (It was was more common in Classical Chinese, but modern Chinese prefers character pairs. Chinese dialects outside of Mandarin are also more forgiving towards single character words. Mandarin though, which is the standard today, loves character pairs.)

Side note: this means that

this^ is a very good guess, and is especially relevant to long kanji chains of the sort you can see in titles of official Japanese documents. Knowing that kanji often pair up makes guessing how to parse things much easier. Congratulations, @idrinktoomuchcoffee! :grin: However, this point is probably slightly more relevant to Chinese than to Japanese.

However, the other half of the issue is this: just because two things can be translated with the same word in English does not mean they mean exactly the same thing in Chinese or Japanese. I think I’ve expressed this once before on the WK forums, but the thing about kanji is that they’re rarely like words in English. Words in English stand alone. Kanji are more like… word elements. You know, prefixes, suffixes and word roots. However, it doesn’t stop there: kanji are very often interlinked, with their basic meaning often being drawn from whatever they meant at their inception. As such, what it’s really like to understand a kanji is… you know those visual thesauri that show each word as a node on a graph, a point connected to a whole bunch of other words? That’s what kanji are like. It’s a web of information, with each and every node connected to many, many other nodes. By seeing what each kanji is associated with, and how it’s commonly used, you gain a better idea of what exactly it means. It’s as though you’re trying to triangulate the position of something precisely by using what’s around it.

Why is this necessary? Well, it’s because different kanji express different precise nuances. For example, why is it that both 適切 and 適当 can mean ‘suitable’, but only 適当 (in Japanese) acquired the additional meaning of ‘irresponsible’ in the sense of ‘doing only the bare minimum/just enough to take care of things’? Well, 当 additionally has the meaning of being ‘equal’ to something or to ‘treat as’ something. In other words, 適当 is a sort of ‘matching suitability’ that corresponds to the situation at hand, which might explain why, at someone’s discretion, it can also express ‘suitably taking care of’ something by simply doing it any which way. On the other hand, 切 carries an idea of ‘closeness’ and even of ‘urgency’, meaning that 適切 is a sort of suitability that ‘sticks’ to the situation and comes as close as possible to what’s needed. This entire analysis is just a my own hypothesis, but if you look at the meanings of the two kanji that are swapped, you can see why it was easier for 適当 to develop that sort of secondary meaning.

Now then, to return to your words, @resting_potato

First of all, generally speaking, you could see this as a form of euphonic semantic reinforcement, at least in the case of Mandarin. That is, characters are being put together just because the result sounds good and it reinforces the original meaning of each one. However, that’s not the full story. Just like in the examples I raised earlier, while each kanji means something similar, there are finer nuances within each that help us to choose a specific semantic field (i.e. to reuse my graph/map analogy, we’re using two kanji to help us select a line segment within the graph that tells us exactly where we are in terms of meaning). Here we go:

林 is a forest, yes, but as you can see from the number of trees, it simply expresses plurality: there are multiple trees, but that’s about all you know. If you compare it with 森, however, you’ll notice two things: there are more trees in 森, and they’re packed more closely together. That’s exactly the difference between the two (both my Chinese and Japanese monolingual dictionaries roughly agree on this): 林 just means you have quite a few trees, and there’s definitely more than one; 森 means you have lots of trees, and they’re densely packed. The entire set probably also covers a large area. So what’s 森林? Well, you combine the meanings of the two: there are lots of trees, densely packed, in a large area, and if you count the number of 木 in both kanji, you now have five. That means that, while it’s definitely more similar to 森, and you could probably use 森 and 森林 as synonyms in Japanese, you’re placing emphasis on the fact that there are even more trees, and perhaps you’re even combining the parts that are more like 森 (the denser bits) and the parts that are more like 林 (the bits where the trees are further apart). Again, this is just a hypothesis, but I think that with 森林, you’re talking about something even bigger than 森, and you’re really emphasising the number and density of the trees.

In modern Mandarin, 睡 can stand alone. 眠 cannot. I just wanted to put this out there in order to prove that at the very least, in the source language (Chinese), at least one of these was capable of functioning alone at some point, as many kanji could in Classical Chinese. However, yes, in Japanese, neither of these can stand alone.

What’s the difference then? My Japanese monolingual dictionary isn’t helping because under kanji definitions, it defines each one exactly the same way. しょうがない。I’ll bring out the Chinese dictionary instead: according to that dictionary, 睡 can also mean ‘to lie down’ or ‘(of a bed) to accommodate (a person)’. It also now has colloquial meanings (in modern Mandarin) that involve being ‘in bed’ with someone. Point is though, we can see that 睡 is more closely linked to the act of getting into bed or lying on it. That’s how it’s associated with sleep. How about 眠? Well, if you look at the compounds in which it’s used (we’re going into triangulation mode again), you’ll notice that 眠 is very closely associated with sleep itself. That is, it’s associated with the state of being asleep. The physical acts of getting into bed or lying in bed have very little to do with it: it’s all about being unconscious and slumbering. Therefore, 睡眠 refers to the entire process of the sleep: the physical, positional aspect (睡) and the bodily state (眠).

OK, I don’t think I can tell you why, but the difference between 中 and 央 is one of precision. 中 just refers to the centre in general, and by extension can refer to the interior of something. I think the central vertical stroke is actually a position marker, and you can see that it’s roughly the same distance from each side. That’s how you know it means ‘centre’. 央, on the other hand, refers to the exact centre of something. It has another meaning: ‘to finish’, but that’s much rarer. There’s one more meaning in Chinese – ‘to request’, ‘to beg’ – but I think we can ignore that one for now. Point is though, you might notice that the first two meanings refer to very exact positions. That aside, even if you could call this a matter of preferred abbreviations rather than a matter of meaning… did you know that in China, the CCTV television station is abbreviated as 央視 in longer compounds? Of course, this could be a matter of not confusing it with the 中 of 中国, but I think this suggests that it is 央 that allows 中央 to convey the idea of ‘centre’ more strongly. More importantly, I don’t know if you know this, but 中央 is also used as a modifier to mean ‘central’, as in ‘the central committee’. If you want to name a central authority for things, you want it not only to be roughly in the centre and in the thick of things (中), but exactly in the centre so that everyone can refer to it (央). That’s why both kanji are needed, particularly since it’s rare for 央 to stand on its own: it’s much more common in compounds.

Ultimately, that turned into more of a kanji breakdown and analysis than an answer about etymology. However, I hope this helps you get a better sense of how kanji work and why such kanji compounds (containing two kanji with similar meanings) exist.


The simplest explanation I’ve found so far for how Kanji work!

This is exceedingly interesting because it seems you’d be hard pressed to figure this out unless you learned enough vocabulary using those Kanji and were really paying attention.

Thanks @Encyclopedia @Jonapedia! Reading your answers, even when they are guesses, is very enlightening because, even if you do land up being wrong about something, it gives us an idea about how to think about these things.


Wow thank you so much! I really didn’t expect to get such an in-depth answer. I really love digging into word origins so learning about how they are used in Chinese is fascinating to me.

I did not consider that some of those kanji cannot stand alone. But I understand that. Even in my native language, which is Hungarian, we have some words that work in compound but not alone, though it’s because they are Old Hungarian words that somehow died out except in those compound cases. To give you an example, hónalj means armpit, which is composed of hón, a very old word for shoulder and alj, meaning the underside of something. And while we use alj pretty much every day on its own, we don’t use hón anymore. The new word for shoulder is váll.

I probably rely a bit too much on the dictionary for meanings, but honestly in these beginning phases it’s a lot easier for me to learn a new word if I know how it’s made up. Like 新聞 or 天気, if I break each kanji down into a very basic meaning it makes a lot of sense to me and I can recall them a lot easier later. It would probably be better to use a context dictionary, which I hope to in the future but my Japanese is not that good yet.

And this is exactly how I discovered that similar meaning kanji are added together to for a simial meaning compound word. Thank you for breaking down all my examples, it was super helpful and eye opening :blush: I guess getting to know the nuances of the words is what language learning is all about. I remember being pretty perplexed when I heard someone use the words major and minor for portions of food in English, because those words meant big and small. I guess this is kinda the same thing.

So yeah, I guess this is what I’ve been looking for :slight_smile: Thank you for your reply, much appreciated! And thank you everyone who added their knowledge :smiling_face_with_three_hearts: This thread unlocked a new area of learning for me that I can dig myself into :smiley: ありがとうございました:heavy_heart_exclamation:


It’s OK. I understand. I’m like that when I learn new languages as well. I love breaking things down, especially because I tell myself that once I know what all the parts mean, I can more easily see how they combine in general. For that matter, for Japanese, I’ve started looking out for word roots as much as possible, even though I know that my guesses may be wrong. (For example, I have a theory that ひらく, which is one of the readings of 開く, is a combination of ひろ (as in 広い) and あく, which is the other reading of 開く, which would give it the nuance of ‘opening wide’.) I tell myself that at the worst, I’ll be wrong, but I’ll remember things better.

Anyway, just two quick suggestions:

  1. While I know that not all meanings of a given kanji may fit together, you might want to try reading all the definitions and seeing if you can find a common theme. That might help you get a better idea of what a certain kanji means in general. This works for words too. For example, かける has 15-25 definitions in all the major dictionaries, but almost all of them have an idea of attachment or contact in them. Reducing all those definitions to just one or two concept words is helpful, no?
  2. At some point, you’ll probably want to look into usage examples so you can get a sense of how exactly something is used. Jisho.org already has some of those (and I imagine you already use Jisho, like almost everyone here). However, if you want even more, then you can check out https://ejje.weblio.jp, which draws its data from more dictionaries, including the database powering Jisho. I think many of the examples of Weblio’s site are of a higher quality, with perhaps the exception of those from the Tanaka Corpus (because those were apparently a professor’s compilation of his students’ sentences, so there’s no guarantee that they’ve been checked for correctness).

@Jonapedia, do you know of resources that provide visual maps of Kanji to help understand the nuances better? Not even sure what that would look like…

I think you could find something like this a lot in Asian language. So just don’t over analyze about this too much. You will know the different when you see them and use them enough to know one to use in which context.

Think kanji as an intermediate between letters (which carry sounds) and words (which carry meaning). They may have an underlying idea (which is not always complete), and they cannot always form words on their own, much like not all letters can be a 1-letter word.

Besides, like English or any other language, there will be synonyms and closely related words, which is why there are many ways to translate from one language to another. Like in OP’s example, on one hand you can have a JP-EN dictionary entry like
森林、森、林 ~ forest

but you can also have a EN-JP dictionary entry such as
forest, woodland, woods ~ 森

Not saying they are synonyms, but are close enough to be translated as such in many cases.

Sadly, no. What I described was entirely a mental image. I’ve never seen it being done for kanji, only for English words. The closest thing I’ve seen is a meaning evolution chart in Chinese, but the site on which you can find those isn’t free (there’s a technical way to get around it that doesn’t involve anything illegal, but it’s inconvenient) and has been accused of providing inaccurate/made-up etymology.

The most practical way of doing something close to the mapping I mentioned would be to use a dictionary that lists related words, or which has kanji definitions that include examples of compounds for each meaning. You could try Kanjipedia.jp for that. The problem, as usual, is that almost all these resources are entirely in Japanese. The closest thing I can think of in English is this: Mandarin Chinese Character Dictionary - 中英字典 - YellowBridge

It’s for Chinese though, so you’ll need to keep in mind that not all of the compounds you see exist in Japanese, and that some of the nuances may be slightly different because the senses of certain kanji in Chinese have evolved since the time of Classical Chinese, whereas Japanese tends to retain more of the classical nuances.



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I probably should have thought of putting spaces… Sigh…

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