Ruthless in Malayalam

Malayalam words whose English meaning includes “ruthless”:

ക്രൂര (kroora) — Cruel, ruthless, terrible, horrible.
ക്രൂരന്‍ (krooran) — One who is cruel, terrible or hard hearted, brutal, ruthless, tyrant.
നിര്‍ദ്ദയ (nirddaya) — Ruthless, cruel, merciless.