Dull, repetitious (6)
I believe the answer is:
boring
I believe this is a double definition.
'dull' is the first definition.
(similar in meaning)
'repetitious' is the second definition.
(thesaurus)
(Other definitions for boring that I've seen before include "Tedious and tiring" , "Drilling - it's monotonous" , "Tedious, of no interest" , "Mentally wearying" , "Dull and repetitive, a turn-off" .)