What are “on” and “kun” readings?

Are you wondering what “on” and “kun” mean?
Here is a quick and dirty explanation of the two types of readings you will find in a Japanese dictionary:*

Long, long ago, the Japanese did not have an extensive writing system, but they did notice that the Chinese had a pretty nice set-up going. So, as they interacted with Chinese people, they started to “borrow” some of their writing system.

Sometimes it would go like this:

Japanese person: Hey, what does that character mean for you? (referring to, say, 大)

Chinese person: Oh, that means “big.” We pronounce it “da.”

Japanese person: Nifty. Mind if we use that? We’ll pronounce it “dai,” but close enough.

…and that is basically what “ON” readings are. They are readings that are based (more or less) on the original Chinese pronunciation.

But sometimes this would happen:

Chinese person: Hold on, don’t you already have a word for “big?”

Japanese person: Sure, it’s “ookii.” But we can just use the same kanji for that too.

Chinese person: Uh, don’t you think that will be confusing?

Japanese person: Nah.

…and that is basically what “KUN” readings are. They are readings that are based on the original Japanese pronunciation.

You will notice that ON readings are short (just one or two kana long), as in 大 (だい), and there are usually just one or two ON readings per kanji.

KUN readings, on the other hand, are all over the place. They can be short, as in 木 (き), but the reading can also “overflow” the kanji, as in 忙しい (いそがしい), in which case you will have to memorize which hiragana you have to stick on the end to make the word (these hiragana are called “okurigana”). There can also be a LOT of KUN readings for each kanji, but don’t lose heart, because the readings do get simpler as you learn more kanji.

Have any questions or anything to add? Leave them in the comments!

*This is a very rough explanation to save you some time, so please understand that I am glossing over a LOT.