Is there a term or expression for certain terms that we have lain in a dictionary that we consider useless?

I've researched and I found out that "Pleonasm" is not what I'm referring to. So it's not that.

For example: The term prognosticate -"To prognosticate weather conditions is not a simple matter."

We can simply just use predict or foretell.

All in all, I am asking is there a term that describes such useless terms or ways of talking that we don't ordinarily use or shouldn't use to seem ostentatious or pretentious on a daily basis?

Solution 1:

There are several words that might fit.

Archaic - words or idioms no longer in general use

Outmoded, Outdated, Obsolete - as above

Ostentatious - something used mostly to show off (knowledge, wealth, etc)

Pendantic - ostentatious words, ideas. More interested in being academically accurate than in communicating effectively

Solution 2:

In writing, purple prose fits that description.

In literary criticism, purple prose is prose text that is so extravagant, ornate, or flowery as to break the flow and draw excessive attention to itself. Purple prose is characterized by the extensive use of adjectives, adverbs, zombie nouns, and metaphors. - Wikipedia