Adjective:

নিষ্ঠুর, ঘাতুক, অমর্ষিত, অমর্ষ, ক্রূরমতি, ক্রূর, অকরূণ, দয়াহীন, অসদয়, নিষ্করুণ, ক্ষমাহীন, নির্মম, নির্দয়,

merciless's Usage Examples:

current English usage, is a literal or metaphorical force regarded as merciless, destructive, and unstoppable.

He was also invoked in the merciless killing of Arjuna's son Abhimanyu on 13th day of war, having attacked.

She has been described as a "glamorous but merciless female agent" and a "pale-blue-eyed northern goddess".

Synonyms:

bloody; cutthroat; fierce; pitiless; bowelless; unkind; implacable; mortal; unpitying; hard; uncompassionate; remorseless; ruthless; inclement; tigerish; unmerciful;

Antonyms:

placable; compassionate; soft; clement; merciful; bloodless; kind;