The term "nadir" refers to the lowest point in a particular context, often used in astronomy to describe the point directly beneath an observer on the celestial sphere. In a broader sense, it can signify the lowest point in a person's life or a situation, representing a moment of despair or difficulty. In a more technical context, the nadir is the opposite of the "zenith," which is the highest point in the sky. Both terms are commonly used in fields like astronomy, geography, and even in psychology to describe extremes in various situations or experiences.