un·re·lent·ing 
(ŭn′rĭ-lĕntĭng)
(ŭn′rĭ-lĕntĭng)adj.
1. Having or exhibiting uncompromising determination; unyielding: an unrelenting human rights worker.
2. Not diminishing in intensity, pace, or effort: an unrelenting ice storm.
un′re·lenting·ly adv.