cruel (adj.)
- acute
 - afflictive
 - agonizing
 - animal
 - anthropophagous
 - atrocious
 - barbaric
 - barbarous
 - beastly
 - bestial
 - biting
 - bloodthirsty
 - bloody
 - bloody-minded
 - bowelless
 - brutal
 - brute
 - brutish
 - callous
 - cannibalistic
 - cold-blooded
 - cutthroat
 - demoniac
 - demoniacal
 - devilish
 - diabolic
 - diabolical
 - distressing
 - excruciating
 - fell
 - feral
 - ferocious
 - fiendish
 - fierce
 - flinty
 - go
 - gory
 - grave
 - grim
 - hard
 - harrowing
 - harsh
 - heartless
 - heinous
 - hellish
 - hie
 - homicidal
 - hurtful
 - implacable
 - inclement
 - inexorable
 - infernal
 - inhuman
 - inhumane
 - merciless
 - monstrous
 - murderous
 - outrageous
 - painful
 - paroxysmal
 - pass
 - piercing
 - pitiless
 - poignant
 - pungent
 - racking
 - red-handed
 - relentless
 - remorseless
 - ruthless
 - sadistic
 - sanguinary
 - sanguineous
 - satanic
 - savage
 - self-destructive
 - severe
 - sharp
 - shooting
 - slaughterous
 - spasmodic
 - stabbing
 - stinging
 - subhuman
 - suicidal
 - torturous
 - truculent
 - unchristian
 - uncivilized
 - uncompassionate
 - unfeeling
 - unforgiving
 - unhuman
 - unkind
 - unmerciful
 - unpitying
 - unremorseful
 - unsparing
 - unsympathetic
 - unsympathizing
 - unyielding
 - vicious
 - wolfish
 
Cruel as death, and hungry as the grave.
Love is strong as death; jealousy is cruel as the grave.
Our days begin with trouble here,
Our life is but a span,
And cruel death is always near,
So frail a thing is man.
He knoweth not that the dead are there; and that her guests are in the depths of hell.
I must be cruel, only to be kind:
Thus bad begins, and worse remains behind.