Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
blackguardly is an adjective meaning "lacking principles or scruples". It carries one recorded sense.
lacking principles or scruples
“the rascally rabble”
“the tyranny of a scoundrelly aristocracy”
“the captain was set adrift by his roguish crew”
Definitions, synonyms and semantic relations for blackguardly come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.