Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
pitilessly 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 pitilessly come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.