Glossary of Terms:

1/8-inch jack

An 1/8-inch socket commonly used on portable electronic consumer products such as CD and MiniDisc players; A mono 1/8-inch jack uses two conductors (tip/sleeve), and a stereo 1/8-inch jack uses three conductors (tip/ring/sleeve).

Source: Yamaha

Also refered as:   minijack

Related terms:   1/8-inch plug   TRS   TS   miniplug