"Fiddledeedee" is an interjection that expresses dismissal or disregard for a previous remark. Synonyms for this term could include "balderdash," "nonsense," "piffle," "poppycock," or "rubbish." Other similar expressions could include "hogwash," "drivel," "twaddle," or "malarkey." All of these terms highlight a sense of disbelief and a rejection of the preceding statement. These expressions could be used in various contexts, such as in response to a particularly outlandish claim or to show that someone is not taking a statement seriously. In any case, these synonyms for "fiddledeedee" serve to convey a sense of dismissal and a lack of credibility.