A Polyglot is a person who speaks more than one language fluently.
A polyglot Bible is a Bible that has been written in different languages on the same page. Originally this was Greek, Roman, and Hebrew. There would be different columns on the page for each...
A linguist studies many languages. A polyglot merely knows many.
Jane's father teased her, because Jane studied Italian and French to build on her Latin language skills: her father called her a polyglot.