say it: uhn-in-TEN-shuh-nuh-lee
unintentionally is an adverb meaning "without intention; in an unintentional manner". It carries one recorded sense.
without intention; in an unintentional manner
“she hit him unintentionally”
Definitions, synonyms and semantic relations for unintentionally 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.