Black″guard (�), n. [Black + guard.] 1. The scullions and lower menials of a court, or of a nobleman's household, who, in a removal from one residence to another, 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.
A lousy slave, that... rode with the black guard in the duke's carriage, 'mongst spits and dripping pans.
Webster (1612).
2. The criminals and vagrants or vagabonds of a town or community, collectively.
3. A person of stained or low character, esp. one who uses scurrilous language, or treats others with foul abuse; a scoundrel; a rough.
A man whose manners and sentiments are decidedly below those of his class deserves to be called a blackguard.
Macaulay.
4. A vagrant; a bootblack; a gamin.