不一定

bùyīdìng
  1. not necessarily
  2. maybe

CEDICT

Entry Composition

1 不一 bùyī
  1. to vary
  2. to differ
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