big butt; large ass
Colloquial, often used in casual or slangy contexts to describe someone with large buttocks.
That girl is famous for her big butt.
デカ尻がコンプレックスだったけど、今は気に入ってる。
I used to be self-conscious about my big butt, but now I like it.
Compound of デカ (slang for 'big', from でかい) and 尻 (buttocks).