An irregular feature in a landscape; an undulation.

A winding or sinuosity; spec. an undulation or gentle curve of the ground; a slight hill or hollow; the general grouping of heights and hollows.

A section of land that extends in gentle falls and rises; undulation of the surface of land.

Originally U.S. regional (western) A low rising or undulation on land (rare). In later use Cycling: a low or relatively short hill.