恍然大悟

huǎngrándàwù
(idiom) to suddenly realize; to suddenly see the light

CEDICT

Entry Composition

1 恍然 huǎngrán
  1. suddenly (perceive)
  2. confused; vague; distracted
2 大悟 Dàwù see 大悟縣 Dàwù Xiàn