un·der·side 
/ˈʌndɚˌsaɪd/ noun
plural un·der·sides /ˈʌndɚˌsaɪd/ noun 1 [count] : the bottom side or part of something
▪ the underside of the table 2 [singular] : a part of life, a city, etc., that is hidden and usually unpleasant
▪ The book explores the underside of human nature. ▪ Hollywood's dark underside
▪ the underside of the table
▪ The book explores the underside of human nature. ▪ Hollywood's dark underside
