swan dive

1. A type of forward dive in which one keeps one's legs together and stretches one's arms out to the side while in the air. The arms are then brought above the head just before one enters the water. Wow, that was a beautiful swan dive. I suspect she'll get high marks for it.

2. To suffer a sudden and drastic decline or failure; to plummet, as in value, performance, sales, etc. They were one of the top names in video games in the early 80s, but they went bankrupt after their new home console did a swan dive in 1983. I'll lose my entire fortune if the stock market takes another swan dive.