the earth below; the ground below
Refers to the world or ground below a vantage point, such as from a high place or an aircraft.
From the airplane, the world below looks just like a model.
this world; the earthly realm
Buddhist term contrasting the human world with heavenly realms or the Pure Land.
In Buddhism, this world is considered a place of much suffering.
Looking down at the world below from the observation deck, the city looked like a model.
The quiet of the mountain temple makes you forget the bustle of the world below.
The monk who had secluded himself in the mountains finally decided to descend to the world below.
現世 is the general term for 'this present life' or 'the present world', while 下界 is specifically the Buddhist term contrasting the human world with heaven.
俗世 emphasizes the mundane, secular nature of ordinary life, whereas 下界 is used mainly to contrast the human realm with a heavenly or elevated one.
Compound of 下 (under, below) and 界 (world, realm). The Buddhist sense is a calque from Sanskrit or Chinese Buddhist terminology.