set-top box
noun /ˌset tɒp ˈbɒks/
  /ˌset tɑːp ˈbɑːks/
 - a device that allows digital television from cable, satellite, the internet, etc. to be seen on a television set that does not have this feature built in (= as part of the television)机顶盒(数字电视转接装置,把数字电视信号转换成普通电视信号)