非得

fēiděi
(followed by a verb phrase, then – optionally – 不可, or 不行 etc) must

CEDICT

Entry Composition

1 非 fēi
  1. to not be; not
  2. wrong; incorrect
  3. non-; un-; in-; de-
  4. to reproach; to blame
  5. (coll.) to insist on; simply must
2 得 děi
  1. to have to
  2. must
  3. ought to
  4. to need to