For example, 外れ. Why re? Take 夕べ. Why be? 少ない. Why nai? 入り口. Why ri? The list goes on and on. Now, I get some of these are particles, (ri, na) but why are they included in the vocab word? It’s a very concise question and I don’t want to drag it on.
Because first there was language and then there were Kanji to write the spoken word (imported from China). But only Kanji were too hard to write all the time so the core Kanji for the Meaning got preserved and the other evolved to Katakana (I mean theres still SOME Ateji here and there) . Later on Women developed Hiragana because they weren’t allowed to write officially and it became a big hit.
So now you have words with the same kanji that mean different things. You need okurigana to differentiate them. Basically. 外れる vs 外す. You can not only write 外 because then nobody would know which one/how to say it.
Long history. But if you want to look into it there is tons of research on how Japanese evolved. Most material is probably in Japanese itself though.
But to make it short, first you have language and the writing came later and adapted to the actual language. That’s actually the case for every language. Even english went through different iterations to land at where it is today.
For some of these, the original word was a verb ending in an u sound, and depending on what you do with that u and what it is exactly, you get different results. Ending in an i sound for example is a connection thing, so you connect words together with it, so 入り口 is entering mouth, so entrance. e sounds usually mean nominalization, so turning into nouns, this is what’s happening to 外れ. For the rest it’s prolly just how the Japanese said those words. Wiktionary sometimes has etymology for these words included.
These are both just the stem forms of the verbs, which can function as nouns in many cases. 入る is 五段, so the stem is 入り. 外れる is 一段, so the stem is 外れ.
For a lot of these, it comes down to convention and consensus. Especially for longer words, there’ve been different okurigana usages over time before the “correct” one was chosen.
The basic “rule” seems to be to keep outside of the kanji any parts of the word that can be conjugated and stuff anything that’s left inside the kanji, but sometimes other considerations are used. For example 上がる and 上る could both reliably use the okurigana 上る, but then you wouldn’t have a way to differentiate which is which.
Yeah, it’s not always set in stone. The example you mentioned, @ben12lingo, with 入り口 is often just written as 入口, for example
I’m not really sure what this means, can you elaborate.
The り in 入り口 is the stem from 入る (いる).