I first made the mistake of reading this as じゅっしんこく, only to later realize it is actually しゅっしんくに.
Then I realized why I made the mistake. I always studied KOKU as the reading for compound words (eg. 外国人). After all, Wanikani colors the background pink when I do those onyomi readings. I see all those kanji of 出身国 strung together and think “ahh yes, it must be a compound word, so use KOKU!”
But it was KUNI, not KOKU. How should I have known that? What are some hints that make you realize they are actually two separate vocabulary words connected together, rather than the individual onyomi sounds…?
after I posted that, I did some reflecting…
Maybe I should recognize that shusshin is a vocabulary word i already know, therefore anything that comes after it is an additional vocabulary word…
I don’t think it’s that straightforward unfortunately. 出身者 for instance is しゅっしんしゃ, not しゅっしんもの.
There’s no hard rule as far as I can tell. At best you can identify that certain suffixes tend to always be onyomi and others generally kun. Also technical jargon usually favors onyomi while traditional Japanese vocabulary often forces kun readings.
Also I do find しゅっしんこく in JMdict, and my Android IME accepts it:
I would have thought しゅっしんこく was fine? Where did you see something saying it has to be しゅっしんくに?
(I’m going to guess Google translate or something AI that parsed it weirdly)
But yeah, for the general question… You can take educated guesses and accept that you’ll sometimes guess wrong. When you make a mistake, then you just commit it to memory.
There can be additional conceptual rules for each kanji but it comes with spending more time with it and / or asking specifically a native / ai for expliciting readings contexts usages.
For example for 音 (sound, noise)
On: オン、 イン、 -ノン
Kun: おと、 ね、
Reading concepts:
オン (音): Abstract, formal, jukugo.
おと (音): General Sound or Noise
ね (音): Pleasant or Musical Sound
日本語： 「音楽(おんがく)を聞く時、大きい音(おと)は好きじゃないけど、ピアノの音(ね)は好きです。」
英語：「When I listen to music, i dislike loud sounds but… I like the sound of piano.」
So yeah, if it was indeed Google translate that made you think you were wrong… Just in case it wasn’t clear, never trust Google translate. It’s terrible in lots of ways, but it might be worst at determining kanji readings.
What dictionary did you use to check this? The ones I checked seem to indicate that 出身国 is a vocabulary word with reading of しゅっしんこく. When searched for しゅっしんくに they came back with no matches.
