The phrase "most blathering" refers to someone who speaks incessantly, usually in a way that is irritating or nonsensical. There are several synonyms that can be used to describe someone with this tendency. They may be described as verbose, loquacious, gabby, or chatty. They might be referred to as a motormouth or a chatterbox. Alternatively, they could be described as rambling, tangential, or long-winded. When someone's speech is particularly pointless or insubstantial, they may be said to be prattling or babbling. Although these words carry slightly different connotations, they all capture the essence of someone who talks on and on without much purpose.