一定

yīdìng
  1. surely
  2. certainly
  3. necessarily
  4. fixed
  5. a certain (extent etc)
  6. given
  7. particular
  8. must

CEDICT

Entry Composition

1 一 yī
  1. one
  2. single
  3. a (article)
  4. as soon as
  5. entire; whole; all; throughout
  6. "one" radical in Chinese characters (Kangxi radical 1)
  7. also pr. yāo for greater clarity when spelling out numbers digit by digit
2 定 dìng
  1. to fix; to set; to make definite
  2. to subscribe to (a newspaper etc); to book (tickets etc); to order (goods etc)
  3. to congeal; to coagulate
  4. (literary) definitely