Onyomi (音読み) means "sound reading". When kanji were introduced to Japan from China, centuries and centuries ago, these are the rough pronunciations of the kanji that the Chinese were using back at that time (from the area of China that those kanji were brought over from).
Kunyomi (訓読み) means "instruction reading" (pretty much). Before kanji were introduced to Japan, the Japanese people already had a spoken language for centuries, even though they had no way to write their language. When Japan began using kanji (and later hiragana and katakana) to write their language, they had to chose which kanji had the closest meanings to be the best ones to write each of their native Japanese words with.
Yomi (読み) means "reading". On (音) means "sound". Kun (訓) means "instruction" or "explanation" or something like that...
So onyomi are kinda meaningless sounds, while kunyomi are more like actual native Japanese words.
Now since kanji were introduced to Japan so many centuries ago, many many new words have been made in the Japanese language since then...
Many new words were created by making use of multiple kanji to write the word, using each kanji for its meaning to make up the meaning of the new word. In these multiple kanji words, the sound readings of the kanji (onyomi) were very often what became used as the pronunciation for the word. This is why people say: for words with one single kanji on their own it's usually the KUN reading you should use, and for words which have multiple kanji in them it's usually the ON reading for them.
So basically, neither onyomi nor kunyomi are "Chinese readings". The onyomi come from old Chinese from various different locales withing China. Onyomi are not "Chinese" readings really, but just what Japanese know as the "sound" of the kanji. Modern Chinese language doesn't pronounce the characters the same way as Japanese onyomi at all. Both onyomi and kunyomi are Japanese readings of the kanji.
I simplified that as much as possible, and it may even be wrong... but that's roughly how I understand it and hopefully helps you. ^^
April 30, 2015 at 11:42am