slider
n. countablen. a small control on a screen that you move with your mouse or finger to change a setting, like volume or brightness.
n. a graphical control element that allows users to set a value by moving an indicator horizontally or vertically. Refers to the interface component rather than the value itself.
Move the slider to the right to increase the volume.
The website uses a slider to let customers choose their budget range when searching for a new car.
By adjusting the opacity slider in the photo editor, you can blend the two layers together until the transition looks natural.
From slide + -er. The meaning "small hamburger" was originally used to describe onion-steamed small burgers at White Castle restaurants, formerly spelt "Slyder". Regarding the senses about control devices or widgets: physical sliders (potentiometers serving as rheostats) predate virtual ones (elements in graphical user interfaces), and the virtual ones are so named because their concept is the abstraction of the physical ones; if more explanation on that topic is needed, it is available in the Wikipedia articles on skeuomorphs, icons, and the desktop metaphor.
Commonly used in the context of user interface (UI) design and digital settings.