sciolist
One who exhibits only superficial knowledge; a self-proclaimed expert with little real understanding.
Near-synonyms: dabbler, dilettante, jack of all trades, know-it-all, fachidiot
Where it comes from
From Late Latin sciolus + -ist. First attested at the beginning of the 17th century.
Adapted from the Wiktionary entry sciolist (CC BY-SA 4.0).