nadir: 1. the point of the celestial sphere that is directly opposite the zenith and vertically downward from the observer; 2. the lowest point
—Merriam-Webster

zenith: 1. the point of the celestial sphere that is directly opposite the nadir and vertically above the observer; 2. the highest point reached in the heavens by a celestial body; 3. culminating point
—Merriam-Webster

For the purpose of our discussion today, we will focus on definition 2 for nadir and definition 3 for zenith. I imagine if you are an astronomical enthusiast, you are familiar with the celestial definitions of these words, so we are going to talk about their usage in nonscientific speech.

To put it simply, nadir means the very bottom/worst of something, and zenith means the very top/best of something. In everyday conversation, these words usually relate to an experience. For instance, if you are discussing your career, the zenith may be when you entered the role of company vice president (best point). The nadir may be when you were fired after thirty years of work (worst point).

Here are more examples:

The nadir of Earl’s figure skating was when he broke his pelvis during a failed triple axel.
The zenith of Earl’s figure skating was when he qualified for the Olympics.

The nadir of Betty’s cupcake business was when she accidentally poisoned thirty customers.
The zenith of Betty’s cupcake business was when she won the “best dessert in the city” award.

Quiz
Test your understanding with this quiz. Fill in either nadir or zenith in the blanks below. The answers are at the bottom.

1. Frank felt he reached his _______ when the famous artist wanted to paint his portrait.
2. Tracy was sure her life hit its _______ when the rabid dog ate off her foot.
3. The _______ of Harriet’s competitive eating career was when she broke the record for most hot dogs consumed in twenty minutes.
4. The _______ of Cindy’s movie-going pastime was when she paid nine dollars to see the film Murderous Sea Creatures from the Deep IV, which was rated only one star.

Answers: 1. zenith 2. nadir 3. zenith 4. nadir