The word Ainu means ‘human’ in the language but the actual definition of it has been a mystery until very recently! (Fukasawa, 1998).
Note: 'recently' was used when the book was published back in 1998 and because I have not been able to get a hold of more updated books, this is the term I will have to use. (Shucks).
1998 Ainu Archaeology as Ethnohistory: Iron technology among the Saru Ainu of Hokkaido, Japan, in the 17th Century. Oxford, England: British Archaeology Reports.