How to sign: permitting little if any light to pass through because of denseness of matter
"dense smoke"; "heavy fog"; "impenetrable gloom";
Similiar / Same: impenetrable, heavy
How to sign: 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 mak;