na·dir 
/ˈneɪˌdiɚ/ noun
/ˈneɪˌdiɚ/ noun [singular] formal : the worst or lowest point of something
▪ The relationship between the two countries reached a/its nadir in the 1920s. — opposite zenith
▪ The relationship between the two countries reached a/its nadir in the 1920s. — opposite zenith
