Webster's Revised Unabridged Dictionary · 1913

Rancorous

Rancorous (ran"kẽr*us) , adjective

[Old French rancuros.]

Full of rancor; evincing, or caused by, rancor; deeply malignant; implacably spiteful or malicious; intensely virulent.
So flamed his eyes with rage and rancorous ire. — Spenser