dense
adj.
permitting little if any light to pass through because of denseness of matter
dense smoke|heavy fog|impenetrable gloom
adj.
hard to pass through because of dense growth
dense vegetation|thick woods
Synonym: thick
adj.
having high relative density or specific gravity
dense as lead
adj.
slow to learn or understand; lacking intellectual acuity
so dense he never understands anything I say to him|never met anyone quite so dim|although dull at classical learning, at mathematics he was uncommonly quick|dumb officials make some really dumb decisions|he was either normally stupid or being deliberately obtuse|worked with the slow students
Synonym: dim, dull, dumb, obtuse, slow