No, it is not an adverb. Truthful is an adjective, and the adverb form is "truthfully."
yes it is truthful.
"you are not truthful"
More truthful
comparative degree: more truthful superlative degree: most truthful
He was truthful as he explained what had happened. She was not truthful as she attempted to frame him for the crime.
yes he is very truthful
My sister is really truthful.
Speaking truthfully means being honest and genuine in your words and actions. It involves being transparent and sincere in your communication with others. People who are truthful are trusted and respected for their integrity and reliability.
The jury believed the defendant's statement was truthful.
I was most truthful thsn her
The noun form of the word "truthful" is "truthfulness."