Bloviate, a word coined by the 26th president of the United States, Theodore Roosevelt, refers to speaking in a grandiose or pompous manner. The antonyms for bloviate, would be modest, succinct, and plain spoken. Modest suggests a humble and unassuming manner of speaking that is sincere and straightforward. Succinct implies using few words to express oneself, being concise and to the point. Plain-spoken conjures up a person who speaks plainly and truthfully, avoiding using excessive or elaborate language. All of these words provide a stark contrast to bloviate, which suggests a person who is bloated with self-importance and uses verbose language to communicate their message.