The Free On-line Dictionary of Computing (30 December 2018):

right-click

    To click the right-most mouse button on a mouse
   with more than one button.  This usually performs a different
   function from the left button, e.g. displaying a
   context-sensitive menu (Microsoft Windows), extending the
   selection (X).

   When used as a verb it is often written as two words with a
   space instead of a hyphen.

   (2006-07-09)