— boring
— deadening
— deadly
— draggy
— dull
— earthbound
— ho-hum
— insipid
— institutional
— irksome
— jejune
— mind-numbing
— narcotic
— pedestrian
— ponderous
— prosaic
— prosy
— putdownable
— slow
— soporiferous
— soporific
— tedious
— tiresome
— unamusing
— unanticipated
— unemotional
— unending
— unendurable
— unenthusiastic
— unexciting
— unhandy
— unhindered
— uninitiated
— unintelligent
— unintelligible
— unintentional
— uninterested
— uninterrupted
— unmentionable
— unmindful
— unstimulating
— unwanted
— unwanted plant
— unwind
— wearisome