A person is considered high-flown if he tries to sound smarter or fancier than he really is.

The adjective high-flown particularly comes in handy when you're describing overblown, pretentious writing. You can also describe overly lofty plans as high-flown: "The six year-old's intention to build a tree house with wall-to-wall carpeting, electric lights, and plumbing seemed a little high-flown to me."

Definitions of high-flown

adj pretentious (especially with regard to language or ideals)

high-flown talk of preserving the moral tone of the school”
high-sounding, inflated
making claim to or creating an appearance of (often undeserved) importance or distinction

adj of high moral or intellectual value; elevated in nature or style

“"argue in terms of high-flown ideals"- Oliver Franks”
elevated, exalted, grand, high-minded, idealistic, lofty, noble-minded, rarefied, rarified, sublime
having or showing or indicative of high or elevated character

Sign up, it's free!

Whether you're a student, an educator, or a lifelong learner, Vocabulary.com can put you on the path to systematic vocabulary improvement.