Despite modern connotations, the origins of the word “niggardly” have nothing to do with the racial slur.
The word is an adjective meaning stingy or miserly. It comes from the word niggard, which is Norse. The root is "nigla" meaning “to fuss about all matters.” It can also mean petty or unimportant. On the other hand, the racial slur came from the Spanish, Portuguese and French words for black. The similar sound has made the word "niggardly" a sensitive one.
One of the most famous examples of this confusion happened in 1999, when a white aide to the mayor of Washington DC referenced a certain budget as "niggardly." He got a complaint against him and he resigned. There was later a big movement defending the aide and the use of the word. He returned to work for the mayor, but under a different position.
Check out more details on that controversy, and some other incidents at the source.