Definition 1 of 2
Derived from 'high-fidelity', the word got lost over the generations to mean something exemplar, albeit in a sarcastic manner.
"She thinks she is something hi-fi in her turtle leather shoes."
Added 2011-08-11 by Kakoosnix
Definition 2 of 2
Used to refer to wealthy, upper class people with a sense of loathing.
Added 2011-09-02 by GoodCumbany