"O sylvan Wye! Thou wanderer through the woods,..."
See in text (Lines Written a Few Miles above Tintern Abbey, on Revisiting the Banks of the Wye during a Tour, July 13, 1798)
The word “sylvan” means “wooded” and derives from “Silvanus,” the Roman God of woods and fields. By characterizing the Wye as sylvan, the speaker personifies the river as a “wanderer” of the woods and thanks it for all the times the thought of it has provided a sort of refuge for the speaker.