So lacking in interest as to cause mental weariness. Synonyms: boring, deadening, dull, irksome, slow, tedious, tiresome, wearisome. "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" , "Tedious days on the train" , "The tiresome chirping of a cricket" , "Other people's dreams are dreadfully wearisome"
