The angular extent of what can be seen, either with the eye or with an optical instrument or camera.
The visible horizontal line (in all directions) where the sky appears to meet the earth in the distance.
A specific layer of soil, or stratum
The point at which a computer chess algorithm stops searching for further moves.
Any level line or surface.
The range or limit of one's knowledge, experience or interest; a boundary or threshold.
A cultural sub-period or level within a more encompassing time period.
The range or limit of any dimension in which one exists.