Cuspar

Cuspar is a term with multiple uses in different fields. In astronomy, it refers to the part of the sky that is visible to someone looking towards the north. A cuspar is that part of the horizon which is between the north celestial pole and the zenith.

In nautical terms, a cuspar refers to a line of direction on the horizon, determined by a celestial body or a compass point. This line is essentially the direction from the observer to the celestial body.

The term cuspar can also be used in general navigation, referring to lines of direction on the horizon, often used in conjunction with a compass.

In optics, a cuspar is not a commonly used term, but it could refer to an irregular or recessed shape at the edge of a surface, although this usage is not standard.

The word cuspar is derived from the Latin "cusparis," meaning "digest" or "maw," but the origins of the term's different meanings are unclear, and exact etymology is unknown.