
undulation
ups and downs; highs and lows
この地域は起伏に富んだ地形が続いている。
This region has a landscape of rolling, undulating terrain.
彼の人生は起伏が激しく、波乱に満ちていた。
It was a life full of ups and downs.
山道は起伏が激しく、歩くのに苦労した。
The mountain trail had steep ups and downs, and it was hard to walk.