Webster's Revised Unabridged Dictionary · 1913

Virulence

Virulence , noun

[Compare French virulence, Latin virulentia an offensive odor, a stench.]

1.
The quality or state of being virulent or venomous; poisonousness; malignancy.
2.
Extreme bitterness or malignity of disposition.
Refuted without satirical virulency. — Barrow
The virulence of one declaimer, or the profundities and sublimities of the other. — I. Taylor

Also: Virulency