動詞 undulate:

1. stir up (water) so as to form ripples
   同義詞：ripple, ruffle, riffle, cockle
2. occur in soft rounded shapes
   同義詞：roll
3. move in a wavy pattern or with a rising and falling motion
   同義詞：roll, flap, wave
4. increase and decrease in volume or pitch, as if in waves

形容詞 undulate:

1. having a wavy margin and rippled surface

1. Fields of wheat are undulating in the breeze.
   在微風中起伏著一片麥浪。