3
unresponsive(adjective, coldhearted)
2
coldblooded(unyielding, unforgiving)
2
compassionless(adjective, mean, hard, severe, harsh)
2
feral(adjective, mean, harsh, violent, cruel)
2
fiendish(adjective, pitiless)
2
flinty
2
hard of heart(expression, idiom, malevolence)
2
hardened(adjective, hard, tough, harsh, cruel)
2
hellish(adjective, pitiless)
2
hurtful(adjective, mean, severe, harsh, cruel)
2
monstrous(adjective, severe, harsh, cruel)
2
mortal(adjective, mean, severe, harsh, cruel)
2
murderous(adjective, hard, tough, harsh, violent)
2
rancorous(adjective, mean, harsh, cruel, vicious)
2
sadistic(adjective, mean, harsh, cruel, vicious)
2
tigerish(adjective, violent, cruel, vicious, fierce)
2
uncompromising(adjective, cruel, pitiless, heartless, hardhearted)
2
vengeful(adjective, severe, harsh, cruel)
2
vindictive(adjective, mean, hard, tough, severe)
2
violent(adjective, cruel, vicious, fierce, savage)
10 years ago|6.5k views|share |citing 
APASmart Define. (2016). unmerciful thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/unmerciful/thesaurus/synonyms
ChicagoSmart Define. 2016. "unmerciful thesaurus" https://smartdefine.org/unmerciful/thesaurus/synonyms (accessed September 25, 2026).
HarvardSmart Define 2016, unmerciful thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/unmerciful/thesaurus/synonyms>.
MLASmart Define. "unmerciful thesaurus" 31 March 2016. Web. 25 September 2026. <https://smartdefine.org/unmerciful/thesaurus/synonyms>