- The highest point reached, especially by a celestial body in its daily path across the sky.
- The time at which a celestial body is at its highest point in the sky.
- The climax, pinnacle, or peak of something, especially of a person's career or achievements.
Late 16th century: from french zénith, via latin from greek zenith 'point directly overhead', from zein 'to boil, be hot' (because the sun was thought to be hottest at noon).
- The sun reached its zenith in the sky at noon and began its descent towards the horizon.
- The company was at its zenith, with a record-breaking year of profits and growth.
- The actor's zenith was winning an Academy Award for his leading role in the film.
- The empire reached its zenith in the 16th century, with a vast territory and powerful army.
- The zenith of his success was being elected as the youngest mayor in the city's history.