出典:Wiktionary
From Middle English ourn, ouren, from 古期英語 ūrne and similar forms. Compare mine, thine; also compare and see hern. Displaced in standard speech by the -s form, ours, which see for more.
出典:『Wiktionary』 (2015/05/20 05:46 UTC 版)
Perhaps due to reanalysis of ourn as a shortening of our one or our own.