- 黑箱作业 hēixiāngzuòyè lack of transparencyA process or way of handling things in secret without public oversight; backroom deal.
- 黑箱子 hēixiāngzi black boxblack box used in aviation or systems theory
- 黑箱操作 hēixiāngcāozuò under-the-table manipulationSecret or covert activities that lack transparency, such as rigging elections or back-room deals; also written as [[暗箱操作|暗箱操作|an4 xiang1 cao1 zuo4]]
