1rare On the keyboard of a keypunch: a key used to delete a character or piece of data recorded on a punched card; compare delete key .
2In a graphical user interface: a button which is used to delete a file or piece of data.
Originally with reference to the deletion of parts of diagrams created using a graphics program and a light pen.
3On the keyboard of a computer, smartphone, etc.: a key used to delete the character next to the cursor, a selected piece of text or string of characters, a piece of data, or (in later use also) a file.
4On an electronic device (especially a digital camera) or its remote control: a button used to delete a selected file from the device's memory.
1960s. From delete + button.