Grandiloquent
/ɡrænˈdɪləkwənt/
Definition 1 of 1
Pro Tip 1/3Show of Intelligence
Used to sound smart or to impress people, often unnecessarily. 
His grandiloquent monologue seemed more about displaying his vocabulary than making a clear point.
Pro Tip 2/3Often Overdone
Using grandiloquent language can feel excessive and may confuse people. 
The grandiloquent terms in his book made it hard to read.
Pro Tip 3/3Formal Occasions
It's more fitting for formal events, literary works, or speeches, not casual talk. 
For her inauguration, the mayor chose a grandiloquent tone to inspire the city.