adj. 25B6; adjective
a dense forest : THICK, close-packed, tightly packed, closely set, crowded, compact, solid, tight; overgrown, jungly, impenetrable, impassable.
dense smoke : THICK, heavy, opaque, soupy, murky, smoggy; concentrated, condensed.
(informal) they were dense enough to believe me : STUPID, unintelligent, ignorant, brainless, mindless, foolish, slow, witless, simple-minded, empty-headed, vacuous, vapid, idiotic, imbecilic; informal thick, dim, moronic, dumb, dopey, dozy, wooden-headed, lamebrained, birdbrained, pea-brained; Brit. informal daft.
sparse, thin, clever.