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"
having high relative density or specific gravity; "dense as lead"
hard to pass through because of dense growth; "dense vegetation"; "thick woods"
permitting little if any light to pass through because of denseness of matter; "dense smoke"; "heavy fog"; "impenetrable gloom"
uneducated in the fundamentals of a given art or branch of learning; lacking knowledge of a specific field; "she is ignorant of quantum mechanics"; "he is musically illiterate"
uneducated in general; lacking knowledge or sophistication; "an ignorant man"; "nescient of contemporary literature"; "an unlearned group incapable of understanding complex issues"; "exhibiting contempt for his unlettered companions"
unaware because of a lack of relevant information or knowledge; "he was completely ignorant of the circumstances"; "an unknowledgeable assistant"; "his rudeness was unwitting"