relentlessly.

Etymology tree English relentless Middle English -ly English -ly English relentlessly From relentless + -ly (suffix forming abverbs from adjectives and nouns). Relentless is derived from relent (“(noun) act of relenting or giving way, yielding; (verb) to become less cruel or harsh; to become less intense”) + -less (suffix meaning ‘lacking, without’); and relent from Middle English relenten (“to melt; to soften; to dissolve in water; of weather: to be cool and moist”), from Anglo-Norman relenter, relentir (“to melt; to shrivel; to give up; to slacken”), and also influenced by Middle French ralenter, ralentir (“to abate; to slow down”) (modern French ralentir), from re- (prefix meaning ‘again’ having intensifying effect) + alenter, alentir (“to slow down”) (from Old French alentir, from a- (prefix denoting entering a state or progressing towards a goal) + lent (“slow”) (from Latin lentus (“slow, sluggish”), possibly ultimately from Proto-Indo-European *lentos (“pliant; soft; smooth”)) + -ir (suffix forming infinitives of verbs)).