ON and Kun Readings
As stated above, most kanji have more than one pronunciation. There are two
ways to categorize these pronunciations: ON and Kun readings, which are called the
onyomi and the kunyomi in Japanese.
The ON reading(s) of a kanji character are based on Cantonese and Song dynasty
Chinese pronunciations of the kanji character. However, they are not usually
exactly the Chinese pronunciations, as the Chinese language has sounds that do not
exist in the Japanese language and the Japanese language follows a different consonant-vowel
pattern than the Chinese language. Therefore, they are the Japanese approximation
of the Chinese pronunciation.
For example, the kanji for the number one (一) would be pronounced i
or yi in Chinese. The ON readings for the same kanji are ICHI
and ITSU.
You may have noticed that “ICHI” and “ITSU” were written in all capital letters.
To help distinguish the ON reading(s) of a kanji character from the Kun reading(s),
the ON readings are often written in all capital letters when written in Roman characters
(romaji). They are written in katakana for the native Japanese.
Kun
The Kun reading(s) of a kanji character are the native Japanese pronunciations
of the word the kanji character represents. Since the Japanese had a spoken
language before the Chinese introduced the concept of a written language to them,
they already had their own words for most things and concepts the Chinese kanji
characters described. So in addition to learning the Chinese pronunciations
for kanji characters (which developed into the ON readings), the Japanese
imported their own words into the written language.
For example,the kanji for the number one (一) has the Kun reading hito-,
as used in the word hitori, “one person.”
The Kun reading(s) of a kanji character are usually written in italicized
lower case when in romaji. They are written in hiragana for the native Japanese.