heartless (adj.)

• aloof
• apathetic
• arctic
• autistic
• benumbed
• blase
• blunt
• bowelless
• brazen
• brutal
• callous
• calloused
• case-hardened
• catatonic
• chilly
• cold
• cold-blooded
• coldhearted
• comatose
• conscienceless
• cool
• cruel
• dashed
• dejected
• depressed
• despairing
• despondent
• detached
• discouraged
• disheartened
• disinterested
• dispassionate
• dispirited
• down
• downcast
• downhearted
• drooping
• droopy
• drugged
• dull
• emotionless
• flinty
• frigid
• frosted
• frosty
• frozen
• gutless
• hard
• hard-boiled
• hardened
• hardhearted
• harsh
• hopeless
• hypochondriac
• hypochondriacal
• icy
• immovable
• impassive
• inclement
• indifferent
• inexorable
• inhuman
• inhumane
• insensitive
• insouciant
• insusceptible
• inured
• languid
• lethargic
• listless
• low
• low-spirited
• merciless
• nonchalant
• numb
• numbed
• obdurate
• objective
• obtuse
• passionless
• passive
• pessimistic
• phlegmatic
• pitiless
• relentless
• remorseless
• ruthless
• seared
• self-absorbed
• shameless
• slack
• sluggish
• soporific
• soulless
• spiritless
• stoic
• stonyhearted
• stupefied
• subdued
• suicidal
• supine
• torpid
• unaffectionate
• unblushing
• uncaring
• uncompassionate
• unconcerned
• unemotional
• unfeeling
• unforgiving
• ungallant
• unimpassioned
• unimpressionable
• uninterested
• unkind
• unloving
• unmerciful
• unnatural
• unpitying
• unremorseful
• unresponsive
• unsoldierly
• unsusceptible
• unsympathetic
• unsympathizing
• untouchable
• unyielding
• withdrawn
• woebegone
• world-weary