What is the meaning of Blackguard?

The lowest servant in a household charged with pots, pans, and other kitchen equipment.

An unprincipled contemptible person; an untrustworthy person.

A man who uses foul language in front of a woman, typically a woman of high standing in society.

To revile or abuse in scurrilous language.

To act like a blackguard; to be a scoundrel.

Source: wiktionary.org