Dictionary definition · undulate
verb
- stir up (water) so as to form ripples
- occur in soft rounded shapes"The hills rolled past"
- move in a wavy pattern or with a rising and falling motion"The curtains undulated"
- increase and decrease in volume or pitch, as if in waves"The singer's voice undulated"
adjective
- having a wavy margin and rippled surface
Source: Open English WordNet (CC BY 4.0).