Elysian Fields: Classical. Isle of the Blessed.
Virgil: author of the Aeneid
Tartarus: ruler of the realm of the damned
Anchises: Aeneas's father who guides him through the underworld
Charon: Boatman who takes souls to the underworld
Styx: River that separates the living from the dead
Lethe: River of forgetfulness that souls must drink from before returning to the earthly realm to be born again
Lucifer: Fallen angel who is now known as Satan
Satan: Prince of darkness; the malignant evil force in this world
Hell: Realm of the damned.
Purgatory: An in-between place where those who are not good enough for heaven, but not bad enough for hell, are purified
Limbo: The highest and least bad realm of hell (first circle), where those who lived before the Christian era (like Virgil) and unbaptized babies dwell
Primum Mobile: (First Mover). Highest sphere of heaven, identified with Aristotle's sphere of intelligences that cause motion
Hierarchy of Angels: The angels are characterized in 9 descending orders. The orders differ somewhat in Gregory VII and the Pseudo-Dionysius, but the first three are consistent: Seraphim, Cherubim, and Thrones
Beatific Vision: The sight and presence of God