Density
Etymology
From Latin "densus" (thick, crowded). The word for closely-packed became the precise ratio of mass to volume.
noun · /DEN-sih-tee/
How much mass is packed into a given volume — how heavy a thing is for its size.
What it names
Why size and weight can part ways, so that a small lead ball outweighs a large balloon and why some things float while others sink.
Example
A brick and a loaf of bread can be the same size, but the brick’s far greater density makes it far heavier.
Related idea
Density is mass per volume; mass is the total amount of matter. A supertanker has enormous mass but low enough average density to float, while a small anchor sinks.
See also