- Today's Word
Rancor
RANG-kur
Definition
(noun) Bitter resentment or deep-seated ill will, especially long-lasting.
Example
Years later, his rancor toward his former business partner hadn’t faded.
Fun Fact
Derived from Latin rancere, meaning “to stink,” the word “rancor” evokes something festering over time—resentment that rots rather than heals. Rancor is often irrational but enduring, and it drives some of the most powerful conflicts in history, politics, and literature—where characters are defined by grudges they refuse to let go.
(adjective) Capable of producing the desired result; successful in achieving the intended outcome.
The new treatment proved remarkably efficacious in clinical trials, reducing symptoms in over ninety percent of patients within the first two weeks.
Efficacious derives from the Latin efficax, meaning “powerful” or “effectual,” rooted in efficere — “to bring about” or “to accomplish” — built from ex- (“out”) and facere (“to make” or “to do”). The same root gives us effect, efficient, and efficacy — a family of words all built around the idea of something being done and producing a result. It entered English in the 16th century, used predominantly in medical and philosophical contexts to describe remedies or arguments that actually worked.