A Reprint is when a card which has been featured in a previous pack is re-released in a different pack or as a limited edition in a special edition box or a collective pack such as Dark Beginning 1 or for the OCG Beginner's Edition 1.
Usually, the rarity of a card remains equal or declines when featured in a Reprint-Pack. For example, the "Arms" and "Legs" of Exodia were first released as Ultra Rares in Legend of Blue Eyes White Dragon but were brought back as Commons in Dark Beginning 1, whereas the "head" remained an Ultra Rare. In rare cases the rarity of cards increases, such as with "Fusion Gate" and "Coffin Seller". Increasing the rarity of a card has become somewhat common recently due to the releases of Special Edition cards and Turbo Packs.