1. Literally, to physically invert someone or something. I can't go on those roller coasters that turn you upside down—they make me so nauseous.

2. To carefully examine or search a particular place (often creating a mess in the process). Can you believe I turned the entire house upside down looking for an invitation that was on my refrigerator the whole time?

3. To affect or alter one's outlook, circumstances, or lifestyle, usually negatively. Being rejected by the university that was my top choice turned my whole world upside down. Lena was turned upside down when her mom died, and it took a long time for her to find her way again.

4. To cause or introduce significant changes to something, often as a way of attempting to improve it or change its course. This method of filing is so inefficient that I think it's time to turn the whole process upside down.