Behaving in an attention-seeking manner via presenting oneself on the surface as being intelligent, provocative, important, avant-garde, humorous or significant, yet harboring ulterior motives, typically involving some form of personal gratification or material gain (e.g. advancement in social status, career, wealth, etc.).
Note that using this word is often conflated to be a pretentious act in and of itself, as this word is frequently used as a way to easily discredit people, works of art, ideas or statements while simultaneously boosting one's own status.
"I used to think they were a smart, edgy, fun group of people to hang out with... but as soon as they realized I didn't have anything to offer them in terms of getting more publicity or a book deal or an art gallery gig, they stopped talking to me. I don't even know why I try to be their friend anymore! Pretentious twits."
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Dude #1: "I really like the Three Stooges!"
Dude #2: "Whatever, they're so pretentious."
Dude #1: "Do you even know what that word means?"