na-adjective
gently sloping; gentle; gradual
Describes physical slopes, curves, or inclines that are mild and not steep.
この坂はなだらかで、自転車でも楽に登れる。
This slope is gentle, so you can easily climb it even on a bicycle.
なだらかな丘の上
A small house stands on top of a gently sloping hill.
na-adjective
Used for abstract processes, growth, or manner that is steady, unhurried, and without sudden changes. Also describes a soft, gentle tone of voice.
会議はなだらかに進み、大きな対立はなかった。
The meeting proceeded smoothly, with no major conflicts.
彼女はなだらかな口調で話し始めた。
She began to speak in a gentle tone of voice.