<operating system> (Or "drop-down list") A graphical user interface
component that allows the user to choose one (or sometimes more than one) item from a list.
The current choice is visible in a small rectangle and when the user clicks on it, a list of items is revealed below it.
The user can then click on one of these to make it the current choice and the list disappears.
In some cases, by holding down a modifier key such as Ctrl when clicking, the selection is added to (or removed from) the set of current choices rather than replacing it.