Couldn't find any "real" words, just different forms:
bedull
semidull
undull
Some other words for "dull" are: - boring - uninteresting
The Esperanto words for sharp and dull are akra and obtuza respectively.
Gull, bull, cull, dull, full, pull, mull, null, sull
Some six letter words that end in double letters:accessacrossapogeebamboobefallboo booboohoobungeebypasscaresscoffeecouleecuckoodecreedegreeduressegressembossenrollentreeexcessgoateeharassHawaiilayofflycheemorassmuumuupayoffpeeweepizazzrebuffrecallrecessrefillremissripoffrunoffscrollscruffsetteeshrillsoireesquallstressstrolltarifftattoothrilltoffeetoupeeunlessvoodoo
Dull is being boring, plain, sad, all those types of sad and negative words.
The words waxy, pearly, and dull describe a mineral's luster.
luster
null, pull full bull rull
blunt means dull or rounded, for example: "A knife has a sharp end and a blunt end ."
slupiothisis= means lazy, slow, dull
hardness
· boring · quiet · shy · uninteresting