Source : Webster's Revised Unabridged Dictionary (1913)

Dense \Dense\, a. [L. densus; akin to Gr. ? thick with hair or
   leaves: cf. F. dense.]
   1. Having the constituent parts massed or crowded together;
      close; compact; thick; containing much matter in a small
      space; heavy; opaque; as, a dense crowd; a dense forest; a
      dense fog.

            All sorts of bodies, firm and fluid, dense and rare.
                                                  --Ray.

            To replace the cloudy barrier dense.  --Cowper.

   2. Stupid; gross; crass; as, dense ignorance.

Source : WordNet®

dense
     adj 1: permitting little if any light to pass through because of
            denseness of matter; "dense smoke"; "heavy fog";
            "impenetrable gloom" [syn: {heavy}, {impenetrable}]
     2: closely crowded together; "a compact shopping center"; "a
        dense population"; "thick crowds" [syn: {compact}, {thick}]
     3: hard to pass through because of dense growth; "dense
        vegetation"; "thick woods" [syn: {thick}]
     4: having high relative density or specific gravity; "dense as
        lead"
     5: 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: {dim}, {dull}, {dumb}, {obtuse}, {slow}]