kun and on reading


Hello I recently read the difference between the kun or on readings and
understood it, now I know in which cases to use one or the other reading, but
I still have a question. For example: the kanji 日 have 2 on readings - にち and
じつ(and also two kun reading), then which readings should I use? How do I know
which and when I have to use?




You should learn correct reading for each word. In relatively small number of
cases, multiple readings of given word are possible.

Kanji 日 has also reading に often used in 日本 ("Japan") and its compounds: 日本語
("Japanese language"), 日本人 ("Japanese person") etc.

All _on_ readings of kanji 日 come from Middle Chinese *nyit, so /t/ in Early
Middle Japanese forms of these readings ( _nit_ , _zit_ ) is regularly
expected. _ni_ developed as irregular shortening of _nit_.

Middle Japanese and Early Modern Japanese is known to have had syllable-final
/t/ in Sino-Japanese vocabulary, so despite hiragana/katakana spelling of
these readings there was no vowel after /t/.




You should learn correct reading for each word. In relatively small number of
cases, multiple readings of given word are possible.

Kanji 日 has also reading に often used in 日本 ("Japan") and its compounds: 日本語
("Japanese language"), 日本人 ("Japanese person") etc.

All _on_ readings of kanji 日 come from Middle Chinese *nyit, so /t/ in Early
Middle Japanese forms of these readings ( _nit_ , _zit_ ) is regularly
expected. _ni_ developed as irregular shortening of _nit_.

Middle Japanese and Early Modern Japanese is known to have had syllable-final
/t/ in Sino-Japanese vocabulary, so despite hiragana/katakana spelling of
these readings there was no vowel after /t/.

