Obscure, or difficult to understand.
Opaque; allowing little light to pass through.
Thick; difficult to penetrate.
Slow to comprehend; of low intelligence.
Having relatively high density.
Compact; crowded together.
Being a subset of a topological space that approximates the space well. See the Wikipedia article on dense sets for a mathematical definition.
A thicket.
Unpolished, rough and ready, uncultured, unsophisticated.
Woven from a coarsely spun yarn, (usually also from a coarse material).
A garment made from roughly spun yarn or made from a coarse material.