Etymology
Borrowed from Japanese 外人 (gaijin, “foreigner”), from Middle Chinese 外人 (ngwajᴴ nyin). Compare Mandarin 外人 (wàirén), from Old Chinese 外人 (*ŋʷaːds njin, “foreigner, outsider” < “non-relative”), from 外 (wài, “outside, outer”) + 人 (rén, “person”).