undulate undulate /ˈʌndʒəˌleɪt/

adjective

1. Having a wavy margin and rippled surface  ( undulate )
   having a wavy margin and rippled surface
   

verb

1. () Stir up (water) so as to form ripples  ( cockle , riffle , ruffle , ripple , undulate )
   stir up (water) so as to form ripples
   
2. Increase and decrease in volume or pitch, as if in waves  ( undulate )
   increase and decrease in volume or pitch, as if in waves
    The singer's voice undulated
   The singer's voice undulated
   
3. Move in a wavy pattern or with a rising and falling motion  ( roll , undulate , flap , wave )
   move in a wavy pattern or with a rising and falling motion
    The curtains undulated
   The curtains undulated
    The waves rolled towards the beach
   the waves rolled towards the beach
   
4. Occur in soft rounded shapes  ( undulate , roll )
   occur in soft rounded shapes
    The hills rolled past
   The hills rolled past