For broad terms like "Rush" and "Pledge," depending on who's telling the story, you can have the main character actually say or learn that "Rush is now called recruitment", "rushees are called Potential New Members, or PNMs" and "pledges are called new members".
Coming to the realization that there are new terms might be part of your character's natural learning curve as she goes from total newbie with a lot of outdated ideas or myths, to someone investing herself in the process and perhaps finally reaching the other side of the fence. If done well (and sorry to say, a lot of this stuff isn't), I think that people on both sides - Greek and non-Greek - might enjoy your piece.
Good luck, I love that you're taking a creative writing class "just because"!!
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