say it: TROOTH-fuh-lee
truthfully is an adverb meaning "with truth". It carries one recorded sense.
with truth
“I told him truthfully that I had just returned from my vacation”
“he answered the question as truthfully as he could”
Definitions, synonyms and semantic relations for truthfully come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. .