What does the word weak mean?

Usage examples for weak

  1. Strong in the back and weak in the head- the best of us." – The Hidden Places by Bertrand W. Sinclair
  2. I've been weak enough to be made to look with other's eyes and not my own. – 'Laramie;' or, The Queen of Bedlam. by Charles King
  3. Constance went weak within. – The Indian Drum by William MacHarg Edwin Balmer