複線

复线
fùxiàn
  1. multiple track (e.g. rail)
  2. multilane (e.g. highway)
  3. (math.) complex line

CEDICT

math

Entry Composition

1 複 fù
  1. to repeat
  2. to double
  3. to overlap
  4. complex (not simple)
  5. compound
  6. composite
  7. double
  8. diplo-
  9. duplicate
  10. overlapping
  11. to duplicate
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