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.
The region of the uppermost atmosphere where temperature increases along with the altitude due to the absorption of solar ultraviolet radiation by ozone. The stratosphere extends from the tropopause (10–15 kilometers) to approximately 50 kilometers, where it is succeeded by the mesosphere.