1.  obtuseness(n = noun.cognition) dullness - the quality of being slow to understand;
is a kind of stupidity
has particulars: oscitance, oscitancy
Derived forms adjective obtuse₄, adjective obtuse₃

2.  obtuseness(n = noun.attribute) - the quality of lacking a sharp edge or point;
is a kind of bluntness, dullness
Antonym: acuteness
Derived form adjective obtuse₂

   State or quality of being obtuse. [1913 Webster]

N  insensibility, physical insensibility, obtuseness, palsy, paralysis, paraesthesia, anaesthesia, sleep, hemiplegia, motor paralysis, vegetable state, coma, anaesthetic agent, opium, ether, chloroform, chloral, nitrous oxide, laughing gas, exhilarating gas, protoxide of nitrogen, refrigeration, insensible, unfeeling, senseless, impercipient, callous, thick- skinned, pachydermatous, hard, hardened, case hardened, proof, obtuse, dull, anaesthetic, comatose, paralytic, palsied, numb, dead.