閉集

闭集
bìjí
closed set (math.)

CEDICT

math

Entry Composition

1 閉 bì
  1. to close
  2. to stop up
  3. to shut
  4. to obstruct
2 集 jí
  1. to gather
  2. to collect
  3. collected works
  4. classifier for sections of a TV series etc: episode