The "Hole" Radical

I was doing my reviews just a moment ago and came across 大空 (おおぞら), a word I have previously had zero issues with, and while I got it right this time too, I had to take a moment to make sure I wasn’t forgetting anything, since the upper part of the 空 (くう) kanji looked awfully similar to another kanji I’d learned recently: 究 (きゅう).
As far as I can tell, their upper parts are identical. Yet, in spite of this, they use different radicals to form that upper part. 究 is listed as using the “Hole” radical, while 空 is listed as using the “Legs” and “Roof” radicals.



I went and had a look, and it seems like 空 is the only kanji that uses the “Legs” and “Roof” radicals to create that structure, whereas there are plenty of other kanji that use the “Hole” radical to create it.

I find this pretty confusing, and I think it might be a good idea to perhaps change the 空 kanji’s radical structure so it matches the other, similar-looking kanji, so as to avoid this sort of issue. It just feels off to me that the exact same structure would supposedly use different radicals. Maybe move the 空 kanji up a few levels, since the “Hole” radical is taught later than that kanji is?


I can get onboard with this. A radical is only useful if it is visually unique. Admittedly I don’t know the etymology of radicals, and there may be some historical reason it makes sense to make them separate radicals, but taken from a learner’s perspective, just trying to differentiate the components of kanji, it seems arbitrary.

This is something that you’re going to need to get used to.

As the levels go along and you learn more radicals, they start to combine them to make it more simplified.

They could move it up, but this is not the only example, and there are cases where it’s a pretty big gap between them.


I’m perfectly fine with radicals being combined for the sake of simplicity. I imagine making a mnemonic for something with over a dozen radicals would require writing the better part of a novel for a single kanji, and that’s a tall ask for sure.
It’s more that the same exact structure in entirely separate kanji now has two different ways to be built, and I feel like that creates confusion. More specifically, it’s about a later radical being applicable for an earlier kanji.

EG: I can look at 空 and ask myself “There’s a hole above the construction… What was that one again?” and obviously never arrive at an answer, since the actual mnemonic used for 空 never mentions any holes.
If this is a common occurrence, then that’s somewhat worrying.

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You won’t need to rely on mnemonics eventually. What you’re describing is a problem that really doesn’t occur, because at this point I recognize the earlier level kanji based on their shape, it would be worrying if I had to think of the mnemonic every time I saw a kanji. I don’t think you have to worry about this too much.


There is this thing (Radical choice being inconsistent), as well as Wanikani sometimes might not have big enough Radicals.

I feel that generally have more Radicals, with big enough ones as well; only to miss non-printable ones (images).

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the way they’re written is very different. On 空’s top “radical” you draw it down, to the right a bit, then go upwards (but you will usually just stop at the right part in the case of 空.
穴 you just go down and lift the pen off the paper.

Things like these, it really helps to learn how to write the kanji if you wanna go beyond just seeing a shape and associating it with a meaning.


究 too.

穴 in Kanji tends to transform this way on the top.

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You learn the Hole radical in Level 8, and sky is a level 5 kanji. The ‘legs’ and ‘roof’ radicals aren’t always used together, so you need to learn them separately as well.


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