UNRELENTING
persistent, relentless, unrelenting
(adjective) never-ceasing; “the relentless beat of the drums”
brutal, unrelenting
(adjective) punishingly harsh; “the brutal summer sun”; “a brutal winter”
grim, inexorable, relentless, stern, unappeasable, unforgiving, unrelenting
(adjective) not to be placated or appeased or moved by entreaty; “grim determination”; “grim necessity”; “Russia’s final hour, it seemed, approached with inexorable certainty”; “relentless persecution”; “the stern demands of parenthood”
Source: WordNet® 3.1
Etymology
Adjective
unrelenting (comparative more unrelenting, superlative most unrelenting)
Not relenting; having no pity; not being or becoming lenient, mild, gentle, or merciful
Synonyms: unyielding, hard, stern, cruel
Synonyms
• relentless
Source: Wiktionary
Un`re*lent"ing, a.
Definition: Not relenting; unyielding; rigid; hard; stern; cruel.
– Un`re*lent"ing*ly, adv.
– Un`re*lent"ing*ness, n.
Source: Webster’s Unabridged Dictionary 1913 Edition