忌口

jìkǒu
  1. abstain from certain food (as when ill)
  2. avoid certain foods
  3. be on a diet

CEDICT

Entry Composition

1 忌 jì
  1. to be jealous of
  2. fear
  3. dread
  4. scruple
  5. to avoid or abstain from
  6. to quit
  7. to give up sth
2 口 kǒu
  1. mouth
  2. classifier for things with mouths (people, domestic animals, cannons, wells etc)
  3. classifier for bites or mouthfuls