Main Entry: un·re·lent·ing

Pronunciation: \-ˈlen-tiŋ\

Function: adjective

Date: 1588

1 : not softening or yielding in determination : hard, stern <an unrelenting leader>
2 : not letting up or weakening in vigor or pace : constant <the unrelenting struggle>

— un·re·lent·ing·ly \-tiŋ-lē\ adverb