不曾

bùcéng
hasn't yet; hasn't ever

CEDICT

Entry Composition

1 不 bù
  1. no; not so
  2. (bound form) not; un-
2 曾 céng
  1. once
  2. already
  3. ever (in the past)
  4. former
  5. previously
  6. (past tense marker used before verb or clause)