One who believes that they are truly intelligent, but isn't.
Found largely in college campuses, these people immerse themselves in a certain subject - may it be politics, philosophy, physics, etc - and spend a great deal of their lives memorizing as much as they can about it. In an attempt to prove to the world that they are gifted in the subject area, they talk in-depth about even the smallest facet of the subject, to anybody in earshot who's too polite to stop them; they tend to spin the conversation to do so.
To a temporary acquaintance, this technique usually works, and the listener parts with a feeling that the "expert" is intelligent. Spend time with this person, or perhaps know a little about what they're talking about, and you realize it is all just facts given in verbatim by others who are more intelligent than they could ever hope to be.
A sad thing, really, as those who do it have little else to be proud of, and define themselves by their "intelligence". As such, they will always seek validation for their efforts, but it is important not to call them on this. Instead, simply avoid the person... that is, unless you can't help yourself.
Jack and Sarah: "Oh, hey Jim! How's it going?"
Jim: "Great! I just finished reading an introductory book on string theory! It was a little bit below my reading level, to be honest, but a good read nonetheless! You see, what it has to do with is..."
*5 minutes later*
Jim: "...and that's the basic idea behind string theory! Problematic, yet with the potential to explain everything, eh? I'm really excited for the future!"
Sarah: "Wow! I don't understand that! You're smart!"
Jack: "Well, talk to you later, Jim."
Jack, under breath: "Fucking pseudointellectual..."