Monotonous; adjective; lacking in variety; tediously unvarying.

From “The Metamorphosis” pg 14 of 31: “Hearing these words from his mother made Gregor realise that the lack of any direct human communication, along with the monotonous life led by the family during these two months, must have made him confused- he could think of no other way of explaining to himself why he had seriously wanted his room emptied out.”

From searching this word, I now understand that the family was leading a boring life, with no change or exciting events. The life that they were living lead Gregor to want to have the furniture removed from his room.