ultracrepidarian: (n., adj.) a person who gives opinions beyond his scope of knowledge.
It is in reference to False Authority Syndrome on the web site www.vmyths.com.
I get ultra and arian, it’s the crepid part that I am having problems with. English is not one of my strong points, so out comes the dictionary. The funny thing is crepid is not in the dictionary, or any on-line dictionary.
I got a Latin hit and tried a latin-english dictionary but the meaning, foundation could be knowledge.
I also got a hit on a couple of shoe makers in Rome a while back.
Whoops. The implication being that crepido meaning base, or footing, an ultracrepidarian would be one who is expounding outside the knowledge in which he has a strong footing.
Just as the mythical weaver Arachne was transformed into a spider and thus had and entire order of arthropds named after her, So to did the Roman Crepidarios have his name transformed into a byword of incompetence due to his astoundingly bad counsel.
My ancient history is a little rusty, but Crepidarios isrecorded to have been a very poor advisor to several caesars.