tooltip

About 0.08 uses per million words.

Meaning

1. noun 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.
2. verb To add a tooltip to a user interface element.
3. verb To cause a tooltip to appear by hovering over a UI element.

Similar words

suggestion hint tip hover text pointer text box coachmark label cursor caption

Often followed by

text is appears that for to will control when