n.

1. 地平线[the S]
   The sun has risen above the horizon.

   太阳已从地平线升起。

   At last, they saw an island on the horizon.

   终于他们见到地平线上有一个岛。

2. （知识，经验等的）范围；眼界；视野[C]
   Good novels broaden your horizons.

   好小说开阔人的眼界。

n.

1. the line at which the earth's surface and the sky appear to meet.
   ▸ (also apparent horizon) this line represented as a circle, ignoring irregularities and obstructions.
   ▸ (also true horizon) Astronomy  a great circle of the celestial sphere, the plane of which passes through the centre of the earth and is parallel to that of the apparent horizon.
2. the limit of a person's knowledge, experience, or interest.
3. Geology  & Archaeology  a layer or level of soil or rock with particular characteristics or representing a particular period.