"remorselessly" in the adverb sense
1. mercilessly, pitilessly, unmercifully, remorselessly
without pity in a merciless manner
"he was mercilessly trounced by his opponent in the House"
Source: WordNet® (An amazing lexical database of English)
Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.
View WordNet® License