Is the interjection おう really a Chinese loanword? In Samuel E. Martin's "A Reference Grammar of Japanese", in a section (Chapter 23, p. 1041) on putative etymologies for some Japanese interjections like or , he asserts: > Although others [other interjections] seem like little more than grunts or shouts — aa, yaa, yoo — they may have originated as shortenings of more legitimate etyma; oo 'yea' is, after all, a Chinese loanword. Really? If so, a loan from which Chinese word?

I think Martin has (old form ) in mind. This was not uncommonly used to write _ō_ , especially in Edo times. A famous haiku by Kyorai:

>
> ō ō to / iedo tataku ya / yuki no kado
> "All right, all right!" / I say, but the knocking doesn't stop / at the gate in the snow

However, I agree with the commenters that _ō_ is unlikely to have been borrowed from Chinese at all -- not least because it appears in the Nihon Shoki as , i.e. /wowo/ (which incidentally isn't easy to reconcile with any Chinese pronunciation of /), and only got attached to / later.