/ ˈneɪdɪə/ noun

1. the point of the celestial sphere that is directly opposite the zenith and vertically downward from the observer.天底 antonym zenith
2. the lowest point;[sing.] (written) the worst moment of a particular situation，i.e.:the nadir of his career

nadir n. [天] 天底, 最底点, 最低点习惯用语at the nadir of 在...最下层[低点]

Example sentences:

• It felt as if we had traveled from nadir to zenith.
• Ironically, the high point of the novel occurs when the protagonist reaches her nadir, for only then does she arouse our empathy and emotional involvement.

protagonist:

1. the main character in a play, film/movie or book 戏剧的）主角/故事的）主人公
2. one of the main people in a real event, especially a competition, battle or struggle 现实事件（尤指冲突或争端的）主要参与者, 主要人物
3. an active supporter of a policy or movement, especially one that is trying to change sth