The term use means to interact with fixed devices or items to produce some desired (or undesired) effect or generally anything you can right-click with your character that isn't just selecting. This includes such mundane actions as checking your mail, drinking, eating, fighting (use a weapon), and reading scrolls. It also includes items that say "Use: ..." in their tooltip.

Pointers for using objects
Pointer gear on 32x32 in range to use object
Pointer gear off 32x32 out of range to use object

See also Edit