made of or containing a lot of things or people that are very close together [= thick]
dense undergrowth/forest/woodland/jungle etc
A narrow track wound steeply up through dense forest.
a dense rurally-based population
difficult to see through or breathe in
dense black smoke
not able to understand things easily [= stupid]:
Am I being dense? I don't quite understand.
a dense piece of writing is difficult to understand because it contains a lot of information or uses complicated language
a substance that is dense has a lot of mass in relation to its size:
Water is eight hundred times denser than air.
a densely populated area
—denseness noun [uncountable]