案外
あんがい · angai · JLPT N3 · adverb
unexpectedly
📋 案外 = plan + outside: outside the plan, so it happens unexpectedly
案 (an) means plan or proposal, and 外 (gai) means outside, as in 外国 (foreign country). If something falls outside your plan, it is unexpected. 案外 often marks a pleasant surprise, as in 案外簡単, which means surprisingly easy.
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'.