Coima (Spanish for “a bribe” and an unfortunately common word) comes from the Latin calvor, which means, “to cheat, deceive, trick”.
From that root, we get the English… calumny, which means “slander” (in case you forgot your SAT words or didn’t go to Law School!).
It is easy to see how a word meaning “cheating” transformed into both bribery on one hand, and slander on the other.
The c‑m of coima maps to the c-(l)-mn of calumny, with the “l” having been slurred out over time.