What does it mean the button is _armed_?

Question

What does it mean the button is armed?

Answer 1

It is similar to the pressed state. The difference is that armed means that the mouse remains pressed within the bounds of the button. See this reference for more details.

Answer 2

The button is pressed (but not released)! See this link.

Pressed means either by mouse button (pointer still within button regions) or by space button on keyboard.