n.
1.the line at which the sky and Earth appear to meet
2.the range of interest or activity that can be anticipated
3.a specific layer or stratum of soil or subsoil in a vertical cross section of land
4.the great circle on the celestial sphere whose plane passes through the sensible horizon and the center of the Earth
Idiom of the Day
set upon (someone or something)
to attack someone or something violently
The three young boys set upon the man on the city bus.