IPA: //ˈbækdrɒp//
KK: /ˈbækˌdrɒp/
A large piece of cloth or material that is hung at the back of a stage to create a background for a performance or event.
The theater used a beautiful backdrop of a sunset for the play.
Backdrop → It is formed from "back" (from Old English "bæc", meaning the rear or behind) and "drop" (from Old English "drēopan", meaning to fall). The word "backdrop" refers to a background that falls behind a scene, often used in theater or photography.
Think of something that is 'behind' ('back') and 'falls' ('drop') — that's why a backdrop is the background that sets the scene.
No commonly confused words.