訓読み for 歳: とせ vs. とし


There are two 訓読み readings of 歳: とし and とせ. Looking at はたち (二十歳), a reasonable
hypothesis would be "ち is a contraction of とし". I know very little about sound
shifting in Japanese. Is とせ more recent than とし? Is /si/ -> /se/ (or /i/ ->
/e/) a common phenomenon?




Classical Japanese is not necessarily my forte but here is what I do know.

I would say that the two readings are just as old as each other because they
both appear in Classical Japanese. As far as I know, the reading depends on
the positioning of 「歳」 in a word. Needless to say, I am only talking about
[大和言葉]{やまとことば}, not loanwords from Chinese.

When 「歳」 appears at the beginning of a word or it is used by itself, it is
read 「とし」.

> 「[歳]{とし}」= "year"
>
> 「[歳返]{としかへ}る」= "the year changes" or "the new year comes"
>
> 「[歳長]{とした}く」= "to get old"

When 「歳」 appears in another place in a word, it is read 「とせ」.

> The examples that @Kaji listed
>
> 「[幾年]{いくとせ}」= "(how) many years"
>
> 「[千歳飴]{ちとせあめ}」= "a candy for kids that people buy to pray for longevity"

There might be exceptions out there that I am not aware of. I ask the experts
here to feel free to correct me.




Classical Japanese is not necessarily my forte but here is what I do know.

I would say that the two readings are just as old as each other because they
both appear in Classical Japanese. As far as I know, the reading depends on
the positioning of 「歳」 in a word. Needless to say, I am only talking about
[大和言葉]{やまとことば}, not loanwords from Chinese.

When 「歳」 appears at the beginning of a word or it is used by itself, it is
read 「とし」.

> 「[歳]{とし}」= "year"
>
> 「[歳返]{としかへ}る」= "the year changes" or "the new year comes"
>
> 「[歳長]{とした}く」= "to get old"

When 「歳」 appears in another place in a word, it is read 「とせ」.

> The examples that @Kaji listed
>
> 「[幾年]{いくとせ}」= "(how) many years"
>
> 「[千歳飴]{ちとせあめ}」= "a candy for kids that people buy to pray for longevity"

There might be exceptions out there that I am not aware of. I ask the experts
here to feel free to correct me.

