Synonyms For "Duller" :
1 syllable:
blunt, damp, dense, dim, drab, dumb, flat, mat, matt, matte, mute, numb, pall, slow, soft
2 syllables:
arid, benumb, boring, bovine, dampen, deadened, dreary, heavy, humdrum, irksome, leaden, matted, muffle, muffled, muted, obtuse, sluggish, softened, stupid, subdued, thudding, tone down
3 syllables:
colorless, colourless, deadening, desiccate, inactive, lackluster, lacklustre, lusterless, lustreless, spiritless, tedious, tiresome, unpolished, wearisome
4 syllables:
desiccated, monotonous, uninteresting