The phrase "most blithering" can be defined as someone or something that is extremely foolish, senseless, or unintelligible. There are many synonyms that can be used to describe such a person or situation. A few examples of these synonyms include the following: absurd, asinine, foolish, idiotic, inane, nonsensical, ridiculous, and silly. Each of these words conveys a sense of ridiculousness and stupidity, making them an appropriate choice when attempting to describe someone or something that is blithering. Whether used in a formal or informal setting, these synonyms will help you to communicate your message as effectively as possible.