The best way to learn proper English is to read news report, and watch news on TV. Watching TV shows is a great way to learn casual English, slang words, understand culture reference and humor. If you have already watched these shows then you may recall the words used in the following dialogs.

He can be a bit of an ECCENTRIC.
The Big Bang Theory Season 2, Episode 2

If by "ECCENTRIC"...
The Big Bang Theory Season 2, Episode 2

"An ECCENTRIC man, with tendency
to megalomania which makes him unable"
Money Heist Season 1, Episode 8

when everyone sees
that an ECCENTRIC is holding
Money Heist Season 1, Episode 8

What if I become strange and ECCENTRIC?
The Big Bang Theory Season 10, Episode 23