You probably mean "down in the dumps."
This phrase is informal. It's a "stock phrase" or idiom. You can't figure out the meaning of the phrase from the words in it.
It means "to feel sad, depressed, or discouraged."
"After the U.S. election, half of us are happy and half of us are down in the dumps."
"Don't just sit there feeling down in the dumps. Get up. Take a walk in the sunlight."