外币
wài bì · HSK 6
foreign currency
💱 wài = outside + bì = coin — money from outside your country
外 means outside or foreign, 币 means coin or currency. Together they literally spell out outside-coin, i.e. any currency that is not your own.
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'.