vertical circle

1. 1.

   a great circle on the celestial sphere passing through the zenith and perpendicular to the horizon

   Broadergreat circle

Questions about vertical circle

What does vertical circle mean?

vertical circle means "a great circle on the celestial sphere passing through the zenith and perpendicular to the horizon".

Is vertical circle a common word?

vertical circle is banded "Rare" — specialist or archaic — most readers will not have met it. The band comes from how often the word appears in a large corpus of everyday English, not from an editor's impression.