What does the word "zenith" most nearly mean?

The word "zenith" refers to the highest point or peak, often used in the context of celestial bodies as they reach their highest position in the sky. In a broader sense, it represents the pinnacle of something, such as achievements or experiences. Thus, "pinnacle" is the term that most closely aligns with the meaning of "zenith," as both signify the summit or highest level.

Understanding this term helps in various contexts, whether discussing career achievements, personal goals, or even discussing astronomical events. The other choices—accuracy, depth, and circumference—do not convey this idea of height or peak significance, making them less relevant in relation to the meaning of "zenith."