I. ˌupside ˈdown 1 BrE AmE adverb
[ Date: 1400-1500 ; Origin: up so down 'up as if down' (14-16 centuries) ]
1 . with the top at the bottom and the bottom at the top:
To get the plant out of the pot, turn it upside down and give it a gentle knock.
2 . turn something upside down
a) to make a place very untidy when you are looking for something:
The burglars have turned our house upside down.
b) to cause a lot of change and confusion in a situation or in someone’s life:
the story of a young girl whose life was turned upside down
II. ˌupside ˈdown 2 BrE AmE adjective
in a position with the top at the bottom and the bottom at the top:
an upside down U shape