unspeakable (adj.)
- abominable
- abusive
- appalling
- arrant
- atrocious
- awesome
- awful
- backhand
- backhanded
- bad
- baneful
- base
- beastly
- black
- blamable
- blameworthy
- calumnious
- contumelious
- criminal
- damnable
- dark
- degrading
- detestable
- dire
- disgraceful
- disgusting
- distasteful
- divine
- dreadful
- evil
- exceptional
- execrable
- extraordinary
- fabulous
- flagitious
- flagrant
- foul
- grim
- hateful
- heavenly
- heinous
- hideous
- holy
- horrendous
- horrible
- horrid
- horrific
- horrifying
- humiliating
- improper
- indefinable
- indescribable
- ineffable
- inexpressible
- infamous
- iniquitous
- insolent
- insulting
- inviolable
- inviolate
- knavish
- left-handed
- legendary
- loathsome
- low
- marvelous
- monstrous
- mythical
- naughty
- nefarious
- noncommunicable
- noteworthy
- numinous
- obnoxious
- odious
- offensive
- outrageous
- peccant
- phenomenal
- portentous
- prodigious
- rank
- religious
- remarkable
- repellent
- reprehensible
- reprobate
- repugnant
- repulsive
- revolting
- rotten
- sacred
- sacrosanct
- scandalous
- scurrilous
- shameful
- shocking
- sinful
- spiritual
- stupefying
- stupendous
- terrible
- tragic
- undefinable
- unexampled
- unforgivable
- unmentionable
- unnameable
- unparalleled
- unpardonable
- unprecedented
- untellable
- untouchable
- unutterable
- unworthy
- venerable
- vicious
- vile
- villainous
- wicked
- wonderful
- wrong
