I felt extremely sorry for my misdeeds. The underlined word is an example of----.

In the given sentence, "extremely" is the underlined word. It is an example of an "intensifier". An intensifier is a word that is used to emphasize the strength, degree, or extent of the word that it modifies. In this case, "extremely" intensifies the word "sorry". It shows that the speaker is feeling very sorry for their misdeeds.