The Collaborative International Dictionary of English v.0.48:
Unrelenting \Un`re*lent"ing\, a. Not relenting; unyielding; rigid; hard; stern; cruel. -- Un`re*lent"ing*ly, adv. -- Un`re*lent"ing*ness, n. [1913 Webster]WordNet (r) 3.0 (2006):
unrelentingly adv 1: in a relentless manner; "he worked relentlessly" [syn: relentlessly, unrelentingly]