ectothermic
heterothermic
inhumane
poikilothermic
poikilothermous
apathetic
barbaric
barbarous
brutal
callous
cool
cruel
dispassionate
hard-hearted
heartless
imperturbable
indifferent
inhuman
insensitive
merciless
pitiless
ruthless
sangfroid
savage
steely
stony
thick-skinned
uncaring
unemotional
unexcited
unfeeling
unimpassioned
unmoved
unresponsive
unsympathetic
vicious
atrocious
bloodthirsty
crafty
cynical
dastardly
deliberate
deprave
detestable
ferocious
greedy
shameless
unscrupulous
flooded
warm-blooded