-
dense
['dɛns]
so dense he never understands anything I say to him
-
dim
['dɪm]
never met anyone quite so dim
-
dull
['dəɫ]
"although dull at classical learning, at mathematics he was uncommonly quick" - Thackeray
-
dumb
['dəm]
dumb officials make some really dumb decisions
-
obtuse
[ɑ'btus]
he was either normally stupid or being deliberately obtuse
-
slow
['sɫoʊ]
worked with the slow students