Good Gracious Meaning

(idiomatic, euphemistic, dated) Oh my God.

Example: 1865, Charles Dickens, Our mutual friend, Volume 1:
  "Good gracious no, I hope not!"
1900, L. Frank Baum , The Wonderful Wizard of Oz Chapter 23
  The Silver Shoes took but three steps, and then she stopped so suddenly that she rolled over upon the grass several times before she knew where she was.
  At length, however, she sat up and looked about her.
  "Good gracious!" she cried.