(third-person singular simple present goes south, present participle going south, simple past went south, past participle gone south)
- (idiomatic) To become unfavorable; to decrease; to take a turn for the worse.
- I should have walked away from the casino when my luck went south, but I stayed and ended up in the hole.
- He was unconcerned that his health might turn south.
- Yesterday the stock market moved south, ending up on a loss for the day.
- Afterward, when company profits had ventured a bit too far southward, the CFO began to get nervous.
This idiom is constructed with a variety of terms, all consisting of a verb indicating movement and a direction indicating the movement is to the south (southerly, southward, etc.) The exact construction may be modified to fit the circumstances.