merciless

Having no mercy; cruel.

Destitute of mercy; unfeeling; pitiless; hard-hearted; cruel; relentless; unsparing.

Without hope of mercy.

Synonyms Unmerciful, severe, inexorable, unrelenting, barbarous, savage.

Destitute of mercy; cruel; unsparing; -- said of animate beings, and also, figuratively, of things.