BLACKGUARD n. 6 definitions
had charge of the kitchen utensils, and being smutted by them, were jocularly called the "black guard"; also, the servants and hangers-on of an army. [Obs.] A lousy slave, that . . . rode with the black guard in the duke's carriage, 'mongst spits and dripping pans. Webster (1612).
BLACKLIST v.
To put in a black list as deserving of suspicion, censure, or punishment; esp. to put in a list of persons stigmatized as insolvent or untrustworthy, -- as tradesmen and employers do for mutual protection; as, to blacklist a workman who has been discharged. See Black list, under Black, a. If you blacklist us, we will b…