Pompous or extravagant in language, stile or manner; or intending to impress.
Origin
Grandiloquence, the noun, is dated back to the 1580’s and is compounded of two Latin words- grandis meaning big, and loqui meaning speech. Grandiloquent, the adjective, is probably a back formation from grandiloquence that was first recorded in the 1590’s, only 10 years later than its parent.
Why this word?
This word is pretty much self-explanatory as it is a part of a bigger, a more known family of words such as magniloquent, eloquent, ineloquent and others- many of which have to do with speech.
I love the fact that this big adjective is there to describe people using big adjectives! It reminds me of Hippopotomonstrosesquipedaliophobia, which is the actual word for individuals who fear long words (coming to think about it, there are many medical conditions those suffering from cannot pronounce!).
It is also a great word for another reason- there are so many people among us who feel their regular speech is just not good enough (for who?) and try to making better impression using bigger and more complicated words. On many occasions this effort results in mispronunciation of these words which, in turn, leads to a worse impression then regular speech would have resulted in.
This word simply teaches us to be ourselves!
How to use grandiloquent?
Just as an adjective describing people using big words for the wrong reasons!
“Oof, David is so annoying! Why does he have to be so grandiloquent?? A 3 seconds point takes an hour to understand!”
Or:
“I should seize from my grandiloquent ways. No one seems to have the patience of listening, and those who do- don’t seem to understand me!”