1. The point in the sky directly above an individual: John looked up into the sky after dark and saw the moon at its zenith.
2. High point, peak, best moment: Being elected mayor was the zenith of Bill's political career.
3. Most successful, peak, greatest success: The United States was at its zenith before Donald Trump became President.
4. Etymology: from Arabic samt, "path over the head". The Arabic samt became the English zenith because a medieval scribe copied the word samt incorrectly, making it "senit", which became our zenith.

Another explanation: about 1387, from Old French cenith then French zénith; which came from Medieval Latin (Latin as written and spoken c.700-c.1500) cenit, senit, a bungled scribal transliteration of Arabic samt, "road, path"; an abbreviation of samt ar-ras, literally, "the way over the head".

© ALL rights are reserved.

Go to this Word A Day Revisited Index
so you can see more of Mickey Bach's cartoons.

1. The angle between the direction of interest (of the sun, for example) and the zenith (directly overhead).
2. The angle between the direction to the zenith (point of the celestial sphere vertically overhead) and the direction of a light ray.

A point on the celestial sphere directly above an observer on the earth.

The point 180° opposite the zenith, directly underfoot, is the nadir and the astronomical zenith is defined by gravity; that is, by sighting up a plumb line.

If the line were not deflected by such local irregularities in the earth’s mass as mountains, it would point to the geographic zenith.

Because the earth rotates and is not a perfect sphere, the geocentric zenith is slightly different from the geographic zenith except at the Equator and the poles.

Geocentric zenith is the intersection with the celestial sphere of a straight line drawn through the observer’s position from the geometric center of the earth.