A word and an idiom

One day, another resident here was trying to remember a name and asked me, "What's the name of that polyglot who lives on your floor?"  I turned to her in surprise that she used that word, which I think I've only seen in books and articles and never before heard in a conversation.  The look on my face must have made her think I hadn't a clue what she's just said, so she revised it by saying something like, "Who is that person on your floor who knows a bunch of different languages?"

pol·y·glot /ˈpälēˌɡlät / noun = a person who knows and is able to use several languages.  Example:  "My neighbor Sharon is a translator and is fluent in half a dozen languages besides English."

What does it mean when someone says, "It's all Greek to me"?  Basically, it means that "I don't understand it at all."  Dictionary.com gives this definition:

This expression was coined by Shakespeare, who used it literally in Julius Caesar (1:2), where Casca says of a speech by Seneca, deliberately given in Greek so that some would not understand it, "For mine own part, it was Greek to me."  It soon was transferred to anything unintelligible.