pretentiously
Pretentiously is an adverb that describes an action or way of speaking that is intended to impress others with an artificially grander or more important quality than is actually possessed. It implies an attempt to seem more knowledgeable, sophisticated, or cultured than one truly is, often through affectation or ostentation.
Someone might speak pretentiously by using overly complex vocabulary unnecessarily or by adopting an affected accent.
The term carries a negative connotation, suggesting a lack of authenticity and often a perceived insecurity.