relentless

From relent +‎ -less.

• IPA^(key): /ɹɪˈlɛntləs/

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relentless (comparative more relentless, superlative most relentless)

1. Unrelenting or unyielding in severity.
   • 1930, Norman Lindsay, Redheap, Sydney, N.S.W.: Ure Smith, →OCLC, page 111:

     She sniffed, too, comprehendingly, and fixed her son with a relentless eye.

2. Unremitting, steady and persistent.
   • 2016 January 31, “Is Huma Abedin Hillary Clinton’s Secret Weapon or Her Next Big Problem?”, in Vanity Fair, retrieved 21 January 2016:

     In Clintonworld, the reaction to Grassley’s relentless assault on Huma is one of resignation.

• relentlessness