dense

adjective

1. 1

   slow to learn or understand; lacking intellectual acuity

   so dense he never understands anything I say to him

   never met anyone quite so dim

2. 2

   having high relative density or specific gravity

   dense as lead

3. 3

   hard to pass through because of dense growth

   dense vegetation

   thick woods

4. 4

   permitting little if any light to pass through because of denseness of matter

   dense smoke

   heavy fog