'Relentless' definitions:

Definition of 'relentless'

(from WordNet)
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" [syn: grim, inexorable, relentless, stern, unappeasable, unforgiving, unrelenting]
adjective
Never-ceasing; "the relentless beat of the drums" [syn: persistent, relentless, unrelenting]

Definition of 'Relentless'

From: GCIDE
  • Relentless \Re*lent"less\, a. Unmoved by appeals for sympathy or forgiveness; insensible to the distresses of others; destitute of tenderness; unrelenting; unyielding; unpitying; as, a prey to relentless despotism. [1913 Webster]
  • For this the avenging power employs his darts, . . . Thus will persist, relentless in his ire. --Dryden. [1913 Webster] -- {Re*lent"less*ly}, adv. -- {Re*lent"less*ness}, n. [1913 Webster]

Synonyms of 'relentless'

From: Moby Thesaurus

Words containing 'Relentless'