天てん文もん天てん頂ちょう

noun

astronomical zenith

Rare technical term in astronomy for the point directly overhead in the celestial sphere, as defined by the local vertical.

• 天てん文もん天てん頂ちょうは、観かん測そく者しゃの真ま上うえの天てん球きゅう上じょうの点てんを指さす。

  The astronomical zenith refers to the point on the celestial sphere directly above the observer.