Emily Dickinson Lexicon

RAN'COR, n. [L. from ranceo, to be rank.]

1. The deepest malignity or spite; deep seated and implacable malice; inveterate enmity. [This is the strongest term for enmity which the English language supplies.] It issues from the rancor of a villain. – Shak.
2. Virulence; corruption. – Shak.