Glossary of Terms
 
  1/4-inch plug  
  A 1/4-inch male connector commonly used with electronic musical instruments and professional audio equipment; A mono 1/4-inch plug uses two conductors (tip/sleeve), and a stereo 1/4-inch plug uses three conductors (tip/ring/sleeve).  
  Source: Yamaha  
Also refered as:
  TRS   TS   mono plug   phone plug   stereo plug
Related terms:
  1/4-inch jack   XLR connector   balanced   headphones   input   mono   output   unbalanced