killer app
noun /ˌkɪlər ˈæp/
/ˌkɪlər ˈæp/
(also killer application
(informal) /ˌkɪlər ˌæplɪˈkeɪʃn/
/ˌkɪlər ˌæplɪˈkeɪʃn/
)- a feature or function of a new technology or product that is so useful or popular that it becomes something that everyone or all similar products have to have
- The barcode is one of the killer apps of the digital economy.