Synonyms for Dense:

adj.

all (adjective)
heavy, impenetrable, thick.
compressed, thick (adjective)
close, compact, crowded, heavy, impenetrable, jammed, packed, solid, substantial.
dense (adjective)
cohesive, compact, solid, thick.
dull (adjective)
apathetic, benumbed, besotted, blunt, boorish, bovine, cloddish, comatose, dim, doltish, drowsy, dull, lethargic, loutish, obtuse, ponderous, sleepy, slow, sluggish, soporific, stupefied, thick-witted.
green (adjective)
lush.
heavy (adjective)
gravitational, heavy, leaden, massive, oppressive, pressing, weighty, ponderous.
rocklike (adjective)
hard.
slow, stupid (adjective)
boorish, doltish, dull, dumb, ignorant, lethargic, obtuse, sluggish, thick.
solid (adjective)
concrete, firm, hard, physical, set, stable, substantial, solid.
tight (adjective)
rigid, secure, snug, stiff, taut, tense, tight, firm.
unaware (adjective)
ignorant.

n.

air, airborne, airflow, airless, airy, atmosphere, blast, current, Breathable. algal, androgynous, aquatic, arboreal, aromatic, bare, barren, biennial, bushy, close, creeping, crowded, packed, tighten. confused, confusing, contorted, elaborate, lush, luxuriant, profuse, rank. ability, dopey, idiotic, silly, simple-minded, dimwitted, hebetudinous. bulging, busy, congested, cramped, full, jammed, teeming. counterweight, dead weight, density, light, lightweight, load, net, nett. close together (noun)
close, compact, congested, impenetrable, jammed, packed, solid, thick, tight.
dense (noun)
compact, concentrated, dim, dull, dumb, heavy, impenetrable, obtuse, slow, thick.
slow-witted (noun)
ignorant.

Other synonyms:

airflow, airless, bulging, congested, rank, teeming, Breathable, dimwitted. atmosphere, busy, counterweight, density, dopey, jammed, profuse, hebetudinous. airborne, crowded, dead weight. lightweight, packed. blast, current. air, full. load. net. compact
close.
lush
luxuriant.
Other relevant words:
air, airborne, airflow, airless, atmosphere, bulging, bushy, close, concentrated, congested, counterweight, cramped, crowded, density, dopey, dumb, full, idiotic, ignorant, impenetrable, jammed, lightweight, lush, luxuriant, net, packed, profuse, rank, silly, simple-minded, teeming, Breathable, dimwitted, hebetudinous.

Usage examples for dense

  1. It meant that this was our last chance; but, to my surprise, it did not snow much, the clouds being mostly a dense mist. – Among the Canadian Alps by Lawrence J. Burpee
  2. He was silent and discouraged, while the shade grew still more dense and complete darkness covered him. – En Route by J.-K. (Joris-Karl) Huysmans
  3. However, as only a few at a time could force their way into the dense tangle, the Delawares drove them back with a deadly volley of arrows. – Spotted Deer by Elmer Gregor