I’m a student currently learning Japanese, and I was reading up on some etymologies, when I came across one entry that just doesn’t feel right to me.
The 国語大辞典 and 大辞林 state that ｢果物｣ is a compound of ｢木｣ + ｢だ｣ + ｢物｣ (/ku/ + /da/ + /mono/, literally “tree thing”), with /ku/ being explained as a sound shift from the bounded form /ko/. In support of this, the word ｢獣｣ is cited in comparison, which is explained as a compound of ｢毛｣ + ｢だ｣ + ｢物｣ (/ke/ + /da/ + /mono/, literally “hair thing”).
I can accept the latter, but not so much the former. By this explanation, ｢木｣ has the bounded form /ko/ (from PJ *kɨ → *kə → OJ /kə/ → NJ /ko/), the free form /ki/ (from PJ *kɨ + *i* = *kɨi → OJ /kɨy/ → NJ /ki/), the Azuma dialectal form /ke/ (from OJ /ke/), and now this shifted form /ku/.
Does there exist any other word where four out of a possible five vowels are interchangeable?
There don't seem to be any proposed sound laws that would explain a shift from PJ *ɨ, *ə, or *ɨi → *u, OJ /ə/ or /ɨy/ → /u/, or MJ and NJ /o/ or /i/ → /u/. ｢果物｣ isn’t a particularly common or rare word, so it shouldn’t have any reason to be exempt from them.
If ｢果物｣ were a dialectal form, I would expect to see a more concrete correspondence between /o/ and /u/, such as /kudamumu/ or /kedamunu/, but both these forms are unattested.
The pronunciation /ku/ doesn't exist in any other compounds I can find either, unlike /ko/ in ｢木霊｣ (/kodama/) or ｢木陰｣ (/kokage/).
On these bases, I feel that the claim ｢果物｣ = ｢木｣ + ｢だ｣ + ｢物｣ is untenable.
But what do you guys think? Do you have any suggestions that might resolve this enigma?