In those old Tora-san movies which still play on late-night TV sometimes in Japan (48 were made in the series that had the running title “It’s Not Easy Being A Man”) the main character Atsumi Kiyoshi often ended his goodbyes to friends and loved ones, especially his lady friends, with the word “abayo”. It basically means “goodbye”, but it’s not used very often today. I asked some friends where the word comes from, and this is what I learned:
An online etymological dictionary (in Japanese) has this to say.
According to the article, the most important hypothesis is “ambaiyou 按配よう”. “Ambai 按配” is “condition”. I think that it also connotes “sobriety”. So “abayo” means “Thou shall be in good condition, I pray”, or “Wish you well”.
“Ambai wa ikagateska ? 按配はいかがですか？” would be like the French phrase “Comment ça va ?” [How’s it going?]
I have checked the Kojien.
http://en.wikipedia.org/wiki/K%C5%8Djien
It speculates there that probably the origin of the word “Abayo” was another phrase used in medieval Japan which had the same meaning as “Sayonara”.
The phrase is “Sa-araba-yo”. But it is clear that Kojien is also not sure about it. The explanations ends with a “ka” , in other words with a question mark.