From WordNet (r) 3.0 (2006):
dense
adj 1: permitting little if any light to pass through because of
denseness of matter; "dense smoke"; "heavy fog";
"impenetrable gloom" [syn: dense, heavy,
impenetrable]
2: hard to pass through because of dense growth; "dense
vegetation"; "thick woods" [syn: dense, thick]
3: having high relative density or specific gravity; "dense as
lead"
4: 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"- Thackeray; "dumb
officials make some really dumb decisions"; "he was either
normally stupid or being deliberately obtuse"; "worked with
the slow students" [syn: dense, dim, dull, dumb,
obtuse, slow]