nadir
noun /ˈneɪdɪə(r)/
  /ˈneɪdɪr/
[singular] (formal)- the worst moment of a particular situation- the nadir of his career
- Company losses reached their nadir in 2009.
 Word Originlate Middle English (as an astronomical term): via French from Arabic naẓīr (as-samt) ‘opposite (to the zenith)’.