One's brilliant vocabulary and a tendency to show it off [duplicate]

From Oxford English Dictionary (OED)

I like:

flowery, adj.

Abounding in flowers of speech; full of fine words and showy expressions, florid.

In use:

Shakespeare Measure for Measure (1623) iii. i. 81
Thinke you I can a resolution fetch From flowrie tendernesse?

R. Bage Barham Downs I. 275
Certain flowery gentlemen, who told us, in very pretty language.

I like the term Sesquipedalian

1) having many syllables : long sesquipedalian terms
2) given to or characterized by the use of long words. A sesquipedalian television commentator

Erudite means well-learned, though it does not necessarily connote anything bombastic along with it.

If I was describing a person like this, I might say, "He was exceedingly erudite, and had no qualms about letting you know."

If I needed a phrase, I would say "bombastically erudite."