An Epithet of the River Styx

Book VI of Virgil’s ‘Aeneid’ describes the descent of Aeneas into the underworld, to reach which he must cross the river Styx. I’ve had a quick look at Dryden’s verse translation, but can’t find the actual description of the Styx that you quote. You may like to have a closer look yourself, if you have the time. (If you read Latin, the original is here.)

Even before Virgil, Hesiod described the Styx as one of the rivers of the Underworld. It's never easy in Greek mythology to distinguish the characteristics of the actual river (which was supposed to be corrosive, though it certainly isn't these days), the character of the river-nymph and the wider characteristics conventionally attributed to a stream supposed to flow out of the Underworld ; but it is intersting that the Greek for hatred is stygos.