If you want to impress people, you might try using magniloquent language. That is, fancy and flowery language. For instance, you could use the word magniloquent, which come to think of it, is a magniloquent word itself.
Magniloquent may remind you of the word eloquent, which describes a way of speaking that is articulate, persuasive, and carefully chosen. Magniloquent shares the Latin root loqui, “speak,” with eloquent and also describes a way of speaking. However, magniloquent describes speech that sounds very intelligent and important, but may in fact have little substance. Another adjective that sounds similar and conveys the same meaning is grandiloquent. Other synonyms include bombastic, pompous, and highfalutin.