tooltip
noun/ˈtu(ː)l.tɪp/
Etymology From tool + tip, originally used with toolbars to provide a tip or hint as to what function each graphical icon represented. The term was introduced as ToolTip by Microsoft in the 1990s.
1
Computing, Engineering, Graphical user interface, Mathematics, Natural sciences, Physical sciences, Sciences An element of a graphical user interface in the form of a box of text that appears when a cursor is made to hover over an item; normally used to explain the function of the item.