mentally ill vs unbalanced

mentally ill

adj
  • Having a psychological disorder. 

unbalanced

adj
  • irrational or mentally deranged 

  • of an expression having different numbers of left and right parentheses 

  • not adjusted such that debit and credit correspond 

  • not balanced, without equilibrium; dizzy 

  • an offensive line with more players on one side of the center than on the other 

How often have the words mentally ill and unbalanced occurred in a corpus of books? (source: Google Ngram Viewer )