boring
deadening
dull
ho-hum
irksome
slow
tedious
tiresome
wearisome
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
what an irksome task the writing of long letters is
Edmund Burke
tedious days on the train
the tiresome chirping of a cricket
Mark Twain
other people's dreams are dreadfully wearisome