horizons

plural of horizon

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