用進廢退

用进废退
yòngjìnfèituì

use and disuse; use it or lose it

Wiktionary

Entry Composition

1 用 yòng
  1. to use; to make use of; to employ
  2. (coverb) with; using
  3. to need; to have to (usu. used in the negative or in questions)
  4. usefulness; utility
  5. (bound form) expense; outlay
  6. (courteous) to eat; to drink
  7. (literary) hence; therefore
2 進 jìn
  1. to go forward
  2. to advance
  3. to go in
  4. to enter
  5. to put in
  6. to submit
  7. to take in
  8. to admit
  9. (math.) base of a number system
  10. classifier for sections in a building or residential compound
3 廢 fèi
  1. to abolish
  2. to abandon
  3. to abrogate
  4. to discard
  5. to depose
  6. to oust
  7. crippled
  8. abandoned
  9. waste
4 退 tuì
  1. to retreat; to withdraw
  2. to reject; to return (sth)
  3. to decline