郊外
jiāo wài · HSK 7
outskirt
🏞️ 郊 = suburb + 外 = outside; the outside-of-town zone is the outskirts
外 (wài) is the everyday word for outside or outer, the same 外 in 外国 foreign country. Glue it to 郊 (suburb) and you get the belt that lies outside the city core: the outskirts.
外 — evening 夕 + divination 卜
Originally a compound of 夕 (evening) and 卜 (divination). Ancient Chinese divinations were performed in the morning; doing them at evening (夕) was considered irregular or 'outside' the norm. From this sense of deviation, 外 came to mean 'outside' or 'external'.