say it: MUR-suh-luh-slee
mercilessly is an adverb meaning "without pity; in a merciless manner". It carries one recorded sense.
without pity; in a merciless manner
“he was mercilessly trounced by his opponent in the House”
Definitions, synonyms and semantic relations for mercilessly come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.