boring or uninteresting
cloudy or overcast
lacking brilliance, brightness, or intensity
a dull greenish colour
not resonant or ringing
a dull thud
lacking sharpness of cutting edge or point; blunt
slow in perception or understanding sensibility
lacking activity or vivacity; listless or sluggish
mentally slow; stupid
dullish adj
dullness noun
dully adv
dulness noun
[Old English dol foolish]