日曜日，the different meanings and pronunciations of 日


I am not sure about the pronunciation rules of kanji in Japanese. I understand
that there are several pronunciations for each kanji, and I am wondering how
native speakers decide when to use which pronunciation. Example: In 日曜日, if
I’m not wrong, the first 日 means SUN, pronounced as にち; the second 日 means
DAY, pronounced as び. Is it the case in reality that when the same kanji
expresses the same meaning in a word, it always has the same pronunciation?
Referring back to the previous example, is it true that when 日 means Sun in a
word, phrase or sentence, it always is pronounced にち？




As is the case with other languages, Japanese people parse and read sentences
based on **words** rather than **characters**. English speakers can pronounce
the "rough" part of _rough_ , _through_ and _thorough_ differently without
thinking, and that's because they remember the pronunciations based on words.
Likewise, 日曜日 is a very easy word meaning Sunday, and Japanese people don't
need to worry about the reading of each character every time they see this
word. There are even many
[jukujikun](https://japanese.stackexchange.com/q/24513/5010) like 大人（おとな）,
明日（あした）.

For some kanji, yes, a certain reading is strongly associated with a certain
meaning. For example, the kanji 悪 typically means "bad" or "evil" when read as
あく, but means "sick" or "hatred" when read as お. The kanji 楽 means "leisure"
or "comfortable" when read as らく, and "music" when read as がく. (Most native
speakers are unaware of this; again, they remember the pronunciations based on
words.) However, in many other cases, the association of readings and meanings
of a kanji can seem completely random, and you have to remember each word
individually. Regarding 日, both にち and ひ can mean both "sun" and "day", but
when it means "Japan", it's never read as ひ.




As is the case with other languages, Japanese people parse and read sentences
based on **words** rather than **characters**. English speakers can pronounce
the "rough" part of _rough_ , _through_ and _thorough_ differently without
thinking, and that's because they remember the pronunciations based on words.
Likewise, 日曜日 is a very easy word meaning Sunday, and Japanese people don't
need to worry about the reading of each character every time they see this
word. There are even many
[jukujikun](https://japanese.stackexchange.com/q/24513/5010) like 大人（おとな）,
明日（あした）.

For some kanji, yes, a certain reading is strongly associated with a certain
meaning. For example, the kanji 悪 typically means "bad" or "evil" when read as
あく, but means "sick" or "hatred" when read as お. The kanji 楽 means "leisure"
or "comfortable" when read as らく, and "music" when read as がく. (Most native
speakers are unaware of this; again, they remember the pronunciations based on
words.) However, in many other cases, the association of readings and meanings
of a kanji can seem completely random, and you have to remember each word
individually. Regarding 日, both にち and ひ can mean both "sun" and "day", but
when it means "Japan", it's never read as ひ.

