黑盒

黑盒	hēi hé	black box / fig. system whose internal structure is unknown
黑	Hēi	abbr. for Heilongjiang province 黑龙江
黑	hēi	black / dark / sinister / secret / shady / illegal / to hide (sth) away / to vilify / (loanword) to hack (computing)
盒	hé	small box / case