海外
かいがい · kaigai · JLPT N3 · noun
overseas
🌊✈️ 海外 = sea + outside: whatever lies beyond the sea is abroad
海 (kai) means sea and 外 (gai) means outside. For an island nation like Japan, anywhere past the sea is foreign, so 海外 covers overseas, abroad and foreign, as in 海外旅行 (kaigai ryokō, a trip abroad).
海 — water radical 氵 + 每 (phonetic)
海 is a phono-semantic compound. The 氵 (water) radical signals the meaning—a vast body of water—while 每 supplies the sound. Originally referring to the sea or ocean, it later extended figuratively to mean 'vast' or 'a great quantity,' as in 人海 (a sea of people).
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'.