PITILESSLY

mercilessly, pitilessly, unmercifully, remorselessly

(adverb) without pity; in a merciless manner; “he was mercilessly trounced by his opponent in the House”

Source: WordNet® 3.1

Etymology

Adverb

pitilessly (comparative more pitilessly, superlative most pitilessly)

In a pitiless manner.

Source: Wiktionary

PITILESS

Pit"i*less, a.

1. Destitute of pity; hard-hearted; merciless; as, a pitilessmaster; pitiless elements.

2. Exciting no pity; as, a pitiless condition.

– Pit"i*less*ly, adv.

– Pit"i*less*ness, n.

Source: Webster’s Unabridged Dictionary 1913 Edition