1Unexpectedly, more than one would have thought — an adverb expressing mild surprise that something turned out different from what was assumed.
このケーキ、案外おいしいね。
This cake is surprisingly good.
案外時間がかかってしまった。
It ended up taking more time than I expected.
彼は案外几帳面な性格だ。
He's surprisingly meticulous.
案外、答えは簡単だった。
Surprisingly, the answer turned out to be simple.
2A na-adjective describing something as unexpected or surprising, used as 案外な〜 to modify a noun.
案外な事実が明らかになった。
An unexpected fact came to light.
試合は案外な展開になった。
The match took an unexpected turn.