This is a fun word to roll around on your tongue. I found it in The Hound of the Baskervilles, one of The Greatest Adventures of Sherlock Holmes. I have heard and read it before, but now that I’ve looked it up, I understand it much better. Even before I found the definition, I thought the word seemed like a rolling, waving word, and I find that that isn’t too far from the truth.
Undulating – to move with a wavelike motion, as with a smooth rising-and-falling or side-to-side movement; to have a wavy form or surface
Usage: “It is a wonderful place, the moor,” said [Mr Stapleton], looking round over the undulating downs, long green rollers, with crests of jagged granite foaming up into fantastic surges. “You never tire of the moor. You cannot think the wonderful secrets which it contains. It is so vast, and so barren, and so mysterious.”