• (p. pr. & vb. n.) of Undulate • (a.) Rising and falling like waves; resembling wave form or motion; undulatory; rolling; wavy; as, an undulating medium; undulating ground. Found on http://thinkexist.com/dictionary/meaning/undulating/
To move in waves. Referring to the movement of a female fish's tail in a waving motion used to move gravel for the construction of a redd. Found on http://www.encyclo.co.uk/local/21804