Dishonorable or unscrupulous behavior; the conduct or character of a blackguard.
From 'blackguard' + '-ry' (noun suffix indicating a practice or quality). Similar to how 'witchcraft' and 'villainy' form abstract nouns from person nouns.
Blackguardry was a favorite insult in the 1700s and 1800s when you wanted to suggest someone was behaving like a complete scoundrel—it's more poetic than just calling someone a jerk.
Complete word intelligence in one call. Free tier — 50 lookups/day.