— acerb
— acerbic
— acid
— acidulous
— acrid
— afflictive
— awful
— beastly
— bitter
— blistering
— caustic
— displeasing
— dour
— dreadful
— embarrassing
— forbidding
— god-awful
— grim
— harsh
— hellacious
— hellish
— horrible
— hot
— ill-natured
— mortifying
— nasty
— offensive
— painful
— rebarbative
— repellant
— repellent
— rough
— sharp
— sharp-worded
— sore
— sulfurous
— sulphureous
— sulphurous
— tart
— unbalance
— unbalanced
— unbelief
— unblemished
— unblessed
— unblushing
— unfailing
— unfaltering
— unfeeling
— unflagging
— unflinching
— unfolding
— ungrateful
— unhappy
— unpalatable
— unplanned
— unpleasantness
— unpolished
— unpolluted
— unveil
— unveiled
— unveiling
— virulent
— vitriolic