猝不及防

cùbùjífáng
  1. to be caught off guard
  2. without warning

CEDICT

to be caught off guard; to be taken by surprise

Wiktionary

忽然發生，來不及防備。

重編國語辭典

忽然發生，來不及防備

維基詞典

Entry Composition

1 猝 cù abruptly; suddenly; unexpectedly
2 不及 bùjí
  1. to fall short of
  2. not as good as
  3. too late
3 防 fáng
  1. to protect
  2. to defend
  3. to guard against
  4. to prevent