zenith

Etymology

From Middle English cenyth, from Medieval Latin cenit, from Arabic سَمْت (samt, “direction, path”), from the fuller form سَمْت اَلرَّأْس (samt ar-raʔs, “direction of the head”). The -ni- for -m- is sometimes thought to be due to a misreading of the three strokes, which is plausible, though it could be a mere phonetic approximation.

noun

1. (astronomy) The point in the sky vertically above a given position or observer; the point in the celestial sphere opposite the nadir.
   The 12 day wee had the wind high and large ſo that in two dayes ſaile we made the Sunne our Zenith or verticall point[…] 1638, Sir Thomas Herbert, Some years travels into divers parts of Asia and Afrique
   In this 10th m. appeared that prodigious Comett the tayl whereof was like the blade of a double edged sword, and reached almost from the horizon to the zenith. 1671–1693: Rev. Thomas Jolly, private notebook; printed in: 1895, Henry Fishwick (editor), The Note Book of the Rev. Thomas Jolly: A.D. 1671–1693. Extracts from the Church Books of Altham and Wymondhouses, 1649–1725. And an Account of the Jolly Family of Standish, Gorton, and Altham, page 44
   In the east a pillar of cloud reared from horizon to zenith, with a kind of arm outstretched like a threatening colossus. 1938, Xavier Herbert, chapter XI, in Capricornia, New York: D. Appleton-Century, published 1943, page 180
2. (astronomy) The highest point in the sky reached by a celestial body.
   As far to the west as Monica could see, her world was a sea of fog, […]. Above it arched a cerulean sky; as the sun climbed to the zenith, […], the fog gradually took on a bluish tinge. 1920, Peter B. Kyne, chapter II, in The Understanding Heart
3. (by extension) Highest point or state; peak.
   Winning the continental championship was the zenith of my career.
   There for a while I enjoyed myself in the zenith of glory and pleasure. 1900, William Beckford, The History of the Caliph Vathek, page 173