deadening

1. the act of making something futile and useless (as by routine)

1. 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"