I keep seeing Chanukah being referred to as "the festival of lights". However I don't recall encountering this term in any of the classic religious texts (Talmud, Midrash, Maimonides, Shulchan Aruch, etc.), nor have I ever heard a religious Jew refer to the holiday as anything other than Chanukah. Is there any traditional source for this term or is it just a borrowed term from other religions?
It seems to have been referred to this way at least as early as the time of Flavius Josephus.
Now Judas celebrated the festival of the restoration of the sacrifices of the temple for eight days, and omitted no sort of pleasures thereon; but he feasted them upon very rich and splendid sacrifices; and he honored God, and delighted them by hymns and psalms. Nay, they were so very glad at the revival of their customs, when, after a long time of intermission, they unexpectedly had regained the freedom of their worship, that they made it a law for their posterity, that they should keep a festival, on account of the restoration of their temple worship, for eight days. And from that time to this we celebrate this festival, and call it Lights. I suppose the reason was, because this liberty beyond our hopes appeared to us; and that thence was the name given to that festival.