field of vision; visibility; view
Refers to the area one can see, or the condition of being able to see. Often used in contexts like driving, weather, or personal perspective.
Visibility got poor because of the snow.
Visibility is poor due to fog.
彼の視界には誰もいなかった。
There was no one in his field of vision.
A mountain came into view in the distance.
A large truck blocked my view.
As I climbed the mountain, the view opened up.
The ship quickly disappeared from view.
見通し is commonly used for visibility conditions (e.g. weather, driving) and can also mean a future outlook, while 視界 is the more neutral, physical term for one's field of vision.
Compound of 視 (shi, 'seeing') and 界 (kai, 'world' or 'boundary'), literally 'the world of seeing'.