備胎

备胎
bèitāi
  1. spare tire
  2. (slang) fallback guy (or girl)

CEDICT

slang

Entry Composition

1 備 bèi
  1. (bound form) to prepare; to equip
  2. (literary) fully; completely
2 胎 tāi
  1. fetus
  2. classifier for litters (of puppies etc)
  3. padding (in clothing or bedding)
  4. womb carrying a fetus
  5. (fig.) origin
  6. source
  7. (loanword) tire