What term describes language that is pompous or overblown, often used to conceal a lack of ideas?

The term that most accurately describes language that is pompous or overblown, often used to conceal a lack of ideas, is "bombastic." This term is often applied to speech or writing that uses high-sounding language with little meaning or substance. It implies a sense of arrogance or pretentiousness, as the speaker or writer attempts to impress rather than inform.

Other terms like "verbose" refer to the use of more words than necessary, which may not specifically indicate pomposity, while "complex" relates more to the structure of language rather than its pretentiousness. "Grandiloquent," meanwhile, is closely related and also means lofty or extravagant in language, but "bombastic" captures the essence of language that is meant to impress without substance more sharply. Thus, "bombastic" is the most fitting choice in this context.