底線

底线
dǐxiàn
  1. bottom line; the limit of what one is prepared to accept
  2. (sports) baseline
  3. (sewing) under thread
  4. spy; informer; plant

CEDICT

sports

Entry Composition

1 底 dǐ
  1. bottom; base
  2. background; foundation
  3. copy (of a manuscript or receipt etc) kept as a record
  4. (suffix) end of a year or month
  5. (math.) radix; base (abbr. for 底數 dǐshù)
2 線 xiàn
  1. thread
  2. string
  3. wire
  4. line
  5. (after a number) tier (unofficial ranking of a Chinese city)

classifiers: 條, 股, 根