Example: "Dense smoke"
Example: "Dense vegetation"
Example: "Dense as lead"
Example: "So dense he never understands anything i say to him"
Example: "A compact shopping center"
Having relatively high density.
Compact; crowded together.
Thick; difficult to penetrate.
Opaque; allowing little light to pass through.
Obscure, or difficult to understand.
Being a subset of a topological space that approximates the space well. see wikipedia article on dense sets for mathematical definition.
(of a person) slow to comprehend; of low intelligence.