butt
n. countable B1 Intermediate US //ˈbət// UK //bˈʌt// butt
n. the part of your body that you sit on. It is a common, informal word for your bottom.
n. the fleshy part of the human body that forms the lower back of the torso; the buttocks. Informal in register and generally avoided in professional or academic contexts.
He fell down and landed right on his butt.
After sitting on the hard wooden bench for three hours, my butt was completely numb.
The comedian relied heavily on physical humor, often making himself the butt of the joke by falling over or landing awkwardly on the floor to get a laugh.
Usage
Commonly used in the singular to refer to the area as a whole, though it refers to the pair of buttocks.