जिससे मन ऊब जाए या उबाने वाला।

उसका भाषण मेरे लिए उबाऊ था।
उकताऊ, उचाटू, उबाऊ, ऊबाऊ, पकाऊ

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.
Tedious days on the train.
The tiresome chirping of a cricket.
Other people's dreams are dreadfully wearisome.
boring, deadening, dull, ho-hum, irksome, slow, tedious, tiresome, wearisome