Frodo could understand little of what was said, for the speech that the Silvan folk east of the mountains used among themselves was unlike that of the West.
Of this stream the Silvan Elves made many songs long ago, and still we sing them in the North, remembering the rainbow on its falls, and the golden flowers that floated in its foam.
But the Elves of this land were of a race strange to us of the silvan folk, and the trees and the grass do not now remember them: Only I hear the stones lament them: deep they delved us, fair they wrought us, high they builded us; but they are gone.
There are no more uses of "sylvan" in the book.
Show samples from other sources
The darkness of natural as well as of sylvan dusk gathered over me.
Charlotte Bronte -- Jane Eyre
Laugh at woe and laugh at foe, Menoa’s scion now is safe this night! A forest child we lost to strife; A sylvan daughter caught by life!