vexatious (adj.)

• aggravating
• annoying
• backbreaking
• bothersome
• burdensome
• crushing
• disturbing
• exasperating
• galling
• grueling
• heavy
• hefty
• importunate
• irksome
• irritating
• mean
• onerous
• oppressive
• painful
• pesky
• pestering
• pestiferous
• pestilent
• pestilential
• plaguey
• provoking
• teasing
• tiresome
• troublesome
• troubling
• troublous
• trying
• ugly
• vexing
• wearisome
• wicked
• worrisome
• worrying