The side or edge of a body of water such as a river or pond; the bank or shore; often slightly literary but used in everyday speech.
川のほとりでピクニックをした。
We had a picnic by the riverbank.
あの古い寺は池のほとりに建っている。
That old temple stands on the edge of a pond.
歌の歌詞には『山のほとり』という表現がよく出てくる。
Lyrics often include the expression 'yama no hotori' (by the mountain).