Saying 「おかわり」 when requesting second helping: what is being exchanged?


I am aware that the phrase 「おかわり」 that is used when asking for second helping
(of meals especially) is an idiomatic expression, so its usage is understood
as it is. But, I'm curious about the origin of this phrase because it seems to
be derived from 替わる / 代わる(P) / 換わる, which means "to be exchanged/switched".
How did this phrase come into the usage? Is it the case that in the past when
people asked for second helping, something was exchanged (bowl, chopsticks
etc)?




It means 'replacement'. What is being replaced is the content, not the
container. You can use a related expression `替え` in a wide variety of
replacements. Mostly in Kyusyu area, when you go to a noodle shop, you can ask
for `替え玉`, which is (a ball of) replacement noodle that fills in your empty
bowl still with leftover soup. `替え芯` means a replacement lead for a mechanical
pencil or replacement staples for a stapler.




It means 'replacement'. What is being replaced is the content, not the
container. You can use a related expression `替え` in a wide variety of
replacements. Mostly in Kyusyu area, when you go to a noodle shop, you can ask
for `替え玉`, which is (a ball of) replacement noodle that fills in your empty
bowl still with leftover soup. `替え芯` means a replacement lead for a mechanical
pencil or replacement staples for a stapler.

