空子

kòngzi
  1. gap
  2. unoccupied space or time
  3. fig. gap
  4. loophole

CEDICT

Entry Composition

1 空 kòng
  1. to empty
  2. vacant
  3. unoccupied
  4. space
  5. leisure
  6. free time
2 子 zi noun suffix, as in 椅子 yǐzi "chair"