Grave was the word that was used to describe mass before the word kilogram was introduced. Grave comes from the word gravity and was first used in 1793 in France. The name kilogram was introduced in 1795 but was not the official word for mass until 1875.
In order to have full consistency in the International System of Units (SI), many people think that the kilogram should be called something different. Using the word kilogram creates a problem because it is a base unit that has the prefix "kilo" already in its name. To fix the problem, some people have suggested using the word grave again.