1. N. lies or intentionally deceitful speech.
Example: That entire address was a practiced work of fallaciloquence, not a single word passed fact-checking.
As may be obvious, the word can be divided into “fallacious” and “eloquence”. What’s particularly useful is that second half. You see, the word “eloquence”, in older times, wasn’t merely used to denote a grace of speech. It was used to describe the effectiveness of speech. The alacrity and felicity with which someone can convince another. “Convincing” remains a synonym to this day. All of this traces back to the original Latin term, which directly translates to “speaking out”.
A person who is fallaciloquent is also very good at lying, or at least, that is what is being implied.
So now you have a new word for a sly devil, a used car salesman, a snake-oil man.