unrelenting
I
adjective
adamant, austere, ceaseless, constant, continual, continuous, cruel, determined, diligent, endless, enduring, hard, immitis, implacable, incessant, inclement, indefatigable, inexorabilis, inexorable, inflexible, merciless, obdurate, perseverant, persevering, persistent, pertinacious, pitiless, relentless, remorseless, resolved, rigid, rigorous, ruthless, sedulous, severe, steadfast, stern, stubborn, tenacious, unappeasable, unbending, uncompassionate, uncompromising, undeviating, unforgiving, unmerciful, unpitying, unsoftening, unsparing, unsympathetic, unwavering, unyielding
II
index
brutal, callous, cold-blooded, constant, cruel, dictatorial, diligent, faithful (diligent), immutable, implacable, inexorable, inflexible, ironclad, obdurate, patient, pertinacious, recalcitrant, relentless, remorseless, resolute, rigid, ruthless, sedulous, severe, unbending, uncompromising, undaunted, vindictive
Burton's Legal Thesaurus.
William C. Burton.
2006