How to sign: so lacking in interest as to cause mental weariness
"a boring evening with uninteresting people"; "the deadening effect of some routine tasks"; "a dull play"; "his competent but dull performance"; "a ho-hum speaker who couldn't capture their attention";
Similiar / Same: boring, deadening, ho-hum, irksome, tedious, tiresome, wearisome, slow
How to sign: slow to learn or understand; lacking intellectual acuity
"so dense he never understands anything I say to him"; "never met anyone quite so dim"; "although dull at classical learning, at mathematics he was uncommonly quick"- Thackeray; "dumb officials mak;