I just learned that compound word yesterday.
Ripened languages are words that have taken some time to come into their form. They ripened up, starting with just one kanji, but then became two, or three, or more. That is a compound word or compound kanji. You know that "jukugo" thing I talk about so much? That's this!
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.