Here are several websites about curious, old, and unused words you can use to A) build your vocabulary B) create interesting writing prompts, short story ideas, or plot movements, characters &ETC
For example:
Lucubration /ˌlo͞ok(y)əˈbrāSHən/ noun formal
the act of studying by candlelight ; nocturnal study ; meditation
that which is composed by night; that which is produced by meditation in retirement; hence (loosely) any literary composition
a piece of writing, typically a pedantic or overelaborate one.
Now take lucubration and craft a short story, writing prompt, or simply start writing about what it makes you think of. Use it in a sentence. Write two paragraphs about someone who lucubrates.
Here are great sites that give many many words to learn and choose from. Happy epeoltarification.
Curios Words & Phrases
A decent list of very unusual words like wimbler, squinch, & ailurophile.
Unused Words
Quite a copacetic list, and handily categorized by noun, verb & adjective.
Etymologically Speaking
A curios list of rather familiar words, with a bonus of telling you where they are from, settings, histories galore!
The Encyclopedia of Arda
A swell list of archaic or unusual words used in Tolkien’s works.
The Best Old English Words
Only 13 words, but stupendous nonetheless.
Bizarre, Old, Outdated or Weird Words
A little outdated itself, but still a good list.
Bonus Video! 40 weird words and their origins
The Scribe's Apprentice 