Down In The Mouth Meaning

Example : 1839, Charles Dickens, Oliver Twist, ch. 16:  "Is the old 'un here?" asked the robber. "Yes," replied the voice, "and precious down in the mouth he has been."1940, "Wait Awhile," Time, 15 Jul.:  Said Chrysler's tough, dynamic boss, K. T. Keller: "Don't get down in the mouth about business in this country. There is going to be a lot of money spent here."2006, Howard Kurtz, "In Iraq, Journalist Richard Engel Sticks to the Story," Washington Post, 26 Oct. (retrieved 3 Nov. 2008):  "He was down in the mouth and low on self-confidence," says his mother, Nina Engel.