Years ago, I had read, and then looked up the word for this, but I have since forgotten it, cannot find it, and not being able to recall this word has driven me crazy since.
It's a rarely used or seen word that describes a person who has the ability to, or maybe it was an adjective for just the quailty of ones' speech to be eloquent, spoken with ease and at length and knowledgeably, or at least perceived as knowledgeable/educated on any given topic, via the quality of their speech.
The "at length" part I think was key to include since the word meant more than just being articulate or eloquent in general, it also described the ability to convey a depth of knowledge, whether truly possessed or not.
Something like "the author had the ability to speak _____-ly, and enrapture the audience," or, "the author was _____, able to keep the crowd utterly captivated"
Kind of like a verbosity, but in a good/convincing/skillful way.
It's not a compound word or phrase. It's not / I've searched the thesauruses for erudite / eloquent / articulate / well-spoken / persuasive / verbose / compelling / impassioned / insightful / perspicacious / trenchant... none of them really hit it on the head.
(I think the word was in a Grantland or TheRinger article, FWIT...) Maybe I'm mistakenly conflating the content of the article with another memory of some other word, I sure hope not.
Thanks for any thoughts!