relentless

Unyielding in severity or strictness; unrelenting.

Steady and persistent; unremitting.

Incapable of relenting; unmoved by pity; unpitying; insensible to the distress of others; destitute of tenderness.

Synonyms Implacable, etc. See inexorable, and list under unrelenting.

Unmoved by appeals for sympathy or forgiveness; insensible to the distresses of others; destitute of tenderness; unrelenting; unyielding; unpitying.