adverb
I conscientiously held the baby in my arms, for she was only three months old.
Yes, it is. It is an adjective form of the noun conscience.
The root word "conscientiously" comes from the word "conscience," which refers to one's sense of right and wrong. When someone acts conscientiously, they do so in a way that is guided by their principles and moral beliefs.
The student conscientiously wrote down all his homework assignments for the week he was going to miss school.
part of speech
The part of speech for this particular word is a noun.
The part of speech for "answer" is a noun.
adverb
what part of speech is beneath
The conscientious solider was awarded the honesty award.
The part of speech for "explicit" is an adjective.
The part of speech for "twirl" is a verb.