RMB - Right Mouse Button. Looking for abbreviations of RMB? It is Right Mouse Button. Right Mouse Button listed as RMB. The standard mouse has two buttons, plus a scroll wheel in the middle which sometimes is a button. But most mice do just two things: right- and left-click. Left-click is often referred to as “normal-click” or “regular-click.” Most tasks on a computer can be accomplished solely by using the left mouse button.