The term "blithering idiot" is considered rude and derogatory. Hence, it is best to steer clear of such language. Some synonyms for this term could be "ignoramus," "fool," "nincompoop," or "dolt." Other options could include "dunce," "simpleton," "blockhead," or "moron." One could even opt for less aggressive terms such as "airhead," "scatterbrain," or "space cadet." However, it is crucial to remember that labels and name-calling should not be used to belittle or disrespect anyone. It is always essential to speak with compassion and respect, regardless of the situation or the person involved.