Saturday, March 4, 2017

Kanji Radicals and Components

If you've been learning Japanese for some time you might have heard about the so-called "kanji radicals," or bushu 部首, and wondered exactly what is so radical about kanji? Do they practice skate-boarding? Bungee-jumping? No? Then what's the meaning of "kanji radicals" after all?

Basically, the "radical" of a kanji would be the primary "component" of that kanji. The component which is used to categorize the kanji in a dictionary and that sometimes reveal something about the nature of the kanji itself.

But what are kanji components? Well, one kanji is made up of a number of "components." Each "component" is just a given pattern which shows up across multiple kanji. Some components are based on kanji, which is why some more complex kanji look like they are made out of other, smaller kanji.

The kanji component kuchi 口, "mouth," and how it appears in multiple kanji as a radical and not as a radical.

As we can see above, the component kuchi 口 is very literally a square. Most kanji with a square in it share that component. There is a even a kanji, shina 品, "(commercial) goods," which is made of not one, but three of these squares!

Some kanji with squares have a different square component, though: yon 四 has kunigamae 囗 instead of kuchi 口.

Why Are Radicals Special Components?

Now, you might be asking yourself what makes radicals so special. The thing is, radicals come from Chinese. The way the Chinese language created the hanzi, which was imported to Japanese as kanji, used radicals as lego blocks to make the characters. So they had a proper reasoning for each radical use.

This was millennia ago.

Nowadays that's hardly relevant. Only historians and linguists learn the reasoning behind the radicals. That's because you can't just pick a radical and make up a new kanji for a word. That's not how it works. There's plenty of kanji already made, so you'd rather just use one of those.

How to Use Radicals

Radicals can sometimes be useful for learning Japanese, for a few reasons.

Looking Up Kanji in Dictionaries

The first and foremost reason is that you can look up kanji in dictionaries. Physical, made-of-paper dictionaries use the radicals to index their kanji. Not all the components, only the radical. Which means you need to know which component is the radical to use the index.

In online dictionaries, (like it's much easier because you can filter kanji by any component, not only the radical. And that's a much easier way to find a kanji than it would be to, say, using the extremely useless hardly usable kanji writing recognition feature.

The idea here is very simple. If you find a word you've never seen before with a kanji you've never seen before, it most likely contains components you do have seen before.

So say you find the word nazo 謎, "enigma," and you don't actually know it's pronounced nazo there because there is no furigana there, then you just look up the components: the tall iu 言う thingy ("to say") and the kome 米 one ("rice") and that's how you filter the kanji to narrow it down to 謎. screenshot showing how filtering kanji by radicals is done in an online dictionary.

This can become a frequent thing if you're trying to read stuff without furigana, so I had made an extension for that memorizes that kanji you've looked up with radicals so you don't need to keep filtering it down all the time.

Note that, if you find yourself doing this too much because you're trying to learn Japanese reading manga or something, you might want to read a web novel instead, because then you can just copy-paste the words without looking up each and every kanji.

Writing Kanji

Another thing radicals are good for would be for memorizing how to write kanji. This is because, radicals and components are patterns which multiple kanji share among themselves. So if you know how to write a radical in one kanji, you know how to write that same radical in all kanji.

For example, if you know how to write kuchi 口, you know how to write that same square component in all kanji containing it. Here's a hint: it takes 3 strokes, not 4. Yep. Three strokes, not four. Yeah, I know you normally draw a square with 4 strokes because it has 4 lines, but the kanji component that looks like a square actually takes 3 strokes. Don't ask me. I didn't make the rules.

So instead trying to memorize how to write each kanji individually, you memorize how to write the radicals, you memorize the components of the kanji, and then you have to deal with less memorizing and less confusion.

Counting Strokes

Expanding on the writing part, the radicals help you count the number of strokes in a kanji, which might help you with looking kanji up in a dictionary. It's not extremely useful, but it might come in handy sometime.

Basically, if 力 takes 2 strokes to write and 重 takes 9 strokes to write, then 動 which is made out of those two components must take as many strokes to write as the sum of the strokes it takes to write its components, or 11 strokes in this case.

This is particularly useful in complex kanji that looks like it's made out of other kanji, Like the first kanji of souzou 想像, "imagination," for example. It's made of three components:
  • ki 木 (4 strokes)
  • me 目 (5 strokes)
  • kokoro 心 (4 strokes)
    Heart. Mind. Spirit.

Since 4 + 5 + 4 = 13, we can guess that the 想 kanji has 13 strokes total.

Guessing Meaning of Kanji from Radicals

Now of the most surprising and yet totally unreliable feature of kanji radicals is that in some very, very, very, very rare cases it may let you somewhat guess what a kanji means.

This is seriously totally useless. Incredibly so. Because it's not reliable at all and guessing what text means is not how you read stuff and certainly not how you learn stuff.

Regardless, when a certain radical is placed in a certain position of the kanji, it may tell the nature of that kanji. For example, the kanji of mushi 虫, which means "insect," is contained as a radical in most kanji about insects, always in the same place.

Kanji containing the mushi 虫 radical showing how a radical may hint the meaning of a kanji in some cases.

Now, if you know one thing or two about insects, you might have noticed that an earthworm isn't an insect. They are totally unrelated. Insects are from the phylum Euarthropoda, earthworms are from Annelida. They couldn't have less to do with each other.

That's because radicals are from China, from millennia ago. We didn't have the understanding of animals we have today. At the time, it was thought animals were divided into furry beasts, fishes, birds, and the rest was all mushi 虫. So by this definition:
  • kumo 蜘蛛
    Spider. (a mushi.)
  • kaeru
    Frog. (a mushi.)
  • hebi
    Snake. (a mushi.)

Of course, today, frogs and snakes aren't considered a mushi anymore. The term is now closer to "bug." But the point is: the radical of those words haven't changed.

Added to that: kaze 風, "wind," and tsuyoi 強い, "strong," also have the mushi 虫 component, albeit in a different position, and have nothing to do with bugs at all.

I've also heard that some radicals may hint the reading of kanji, I have never noticed it, though.

Other hints are that some body parts may have the 月 component in it. ude 腕, "arm," ashi 脚, "feet," momo 腿, "thigh," mune 胸, "chest." And so on. And some metals have the 金 component in them. gin 銀, "silver," dou 銅, "copper," etc.

The radicals have their history and logical basis. But it's full of gotchas, exceptions and other complexities. You may gain something from studying it, but it will be a hassle that any Japanese beginner would rather avoid.


Some people make up stories about radicals to use for mnemonics: that is, to remember what the kanji means.

For example, I've heard one about mu 無, "nothing," having a component of fire under it, burning it to "nothing."

That might sound useful... until you consider kuro 黒, "black," also has the fire thing. Plus it's got a sato 里, "village," atop of the fire. What in the world are you implying that means? Are you burning down the village? Is that what kuro means?

Personally I don't think these mnemonics are a good idea. Because there are two thousand kanji out there you ought to learn, and remembering the story behind each and every one of them sounds like a hurdle to me.

They are a good idea in some cases, though.

For example, hidari 左, "left," and migi 右, "right," look very alike, but mean opposite things. You better not to mistake them. I can tell the left one apart because e エ is the first letter of "esquerda," which means "left." Some people can tell the right one apart because kuchi 口 looks like a fist, and for right-randed people that's their right-hand.

Two Radicals vs. Two Kanji

Sometimes it might look like we're writing one word with two different kanji when we're actually writing two radicals in one single kanji.

For example, if you write on'na 女, "woman," and then ko 子, "child," and you join them together, you get joshi 女子, "(young) girl," and that will be one word of two kanji each with one single radical.

However, there is also this thing: 好 which is one kanji made of two radicals. It appears in words such as suki 好き, which mean "to like (something)."

I'd like to note that these two things (女子 and 好) have literally nothing to do with each other. They look alike but they are totally different. It's not like they came up with the kanji for liking things from the word for young girl. That's creepy and I don't want to think about it

Something that's similar to radicals in the Latin alphabet would be accents and diacritics, those things the English language doesn't have. Basically, if you have an accent, like the circumflex ^, and you have a letter, like e, you join them together and you have ê. That's more like how radicals work, because when the components are separated (^e) it looks like math and it's totally different from the letter made of both (ê).

Word Plays with Radicals

Since there's a thin line, or rather, a thin space between two separate kanji and two radicals in one kanji, they can be easy to confuse, and anything that can be confused by accident is going to be confused deliberately in jokes and comedy.

Of course I'm talking about anime, manga and stuff. What blog do you think you are reading?

One notorious case of this is the one in Sayonara Zetsubou-sensei さよなら絶望先生 where the character Itoshiki Nozomu 糸色 望 has a very radical problem. It goes like this:
  • Itoshiki Nozomu 糸色
    His name. It looks alright when written vertically, which is normal in Japanese.
  • Zetsu Nozomu
    When written horizontally, however, his family name looks like the zetsukanji!
  • zetsubou 絶望
    Which makes you think 望 isn't his given name any longer, but the second kanji of the word "despair."

In the story, this gag made an student write his name horizontally with a little extra space between the two kanji to avoid confusion.

Illustration showing how the name of the character Itoshiki Nozomu 糸色望 from the manga Sayonara Zetsubou-sensei さよなら絶望先生 looks like zetsubou 絶望, "despair," when written horizontally because the kanji 絶  is written with the radicals 糸 and 色

I guess this really illustrates how easy you can confuse kanji with radicals but also how different they are.


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  1. "Basically, if 力 takes 3 strokes to write..."
    I guess, you mistyped since sum is correct.

    1. You're right, thanks. I've fixed the typo.

  2. "I've also heard that some radicals may hint the reading of kanji, I have never noticed it, though."

    Yep. There're so called "phonetic radicals". For example, every kanji with 末 radical has on-reading "matsu". Though there're not so many usefull phonetics without exceptions :(

  3. "Personally I don't think these mnemonics are a good idea" I am not into mnemonics either though sometimes it helps. And there is one guy (Vadim Smolensky) who is known as an author of russian kanji-dictionary program (Yarxi) and... as a human being who learned around 8000 kanjis for a reasonable time. He claims that he used his own mnemonic approach.

    For me radicals is the way of remembering new kanji if it's quite complex or if my brain doesnt want to remember it for some reason. Like "what does 'suu' (number) looks like... oh, I remember: rice, woman, chair ))"