What is a word to describe an individual who acts like an expert in a subject area, constantly stating facts and correcting people, but who actually has very little knowledge on the subject?
Cryptonescient Morosophs and Ultracrepidarians
The cryptonescient are best described as morosophs and ultracrepidarians, as any philodox or sumpsimus drawn into this epeolatrous logomachy like a saturniïd to a pharol will deliciate in apprising you with all due impigrity.
Those epithets you may freely employ safe from all risk of nettling even the most inveterate of doryphores, for even if this should fail to deliver the recumbentibus you’re looking for, it should at least jargogle your nemetic opsimath long enough for you to avolate undetected under the supervenient obnubilation.
Charlatan = a person who pretends or claims to have more knowledge or skill than he or she possesses; quack.
This sounds like a poseur (M-W),
a person who pretends to be what he or she is not
In this case, posing as a knowledgeable person.
Although it's a bit general and broad in meaning, my suggestion is pretender:
- a person who pretends, especially for a dishonest purpose.
- a person who makes unjustified or false claims, statements, etc., as about personal status, abilities, intentions, or the like
Could he pretend to be a doctor? He knew a fair bit, from Cathy's pregnancies, her motorcycle accident, his father's stroke, Suzie's addictions. (from Under the Skin by Michel Faber)
Such a person could be described as an armchair expert or armchair pundit.
[as modifier] Lacking or not involving practical or direct experience of a particular subject or activity: an armchair traveller
The result is a unique perspective applauded by armchair naturalists in which the stars of the film are also the videographers.
What do these armchair counter-terrorists propose that Moscow should have done?
Almost all other commentary was grotesque - the work of armchair generals.
See also this article: 'Edward Sapir was not an "armchair linguist"!'