- Oi, an alternative spelling for oy or oy vay, is defined as a Yiddish expression used to express frustration, pain or worry.
An example of oi used as an interjection is in the following sentences: "Oi! I forgot my wallet at home!" which means "Oh no! I forgot my wallet at home!"
oi definition by Webster's New World
oi - Computer Definition
(Operator Interface) A low-level graphical interface to a specialized computer on the plant floor such as a programmable automation controller (PAC), programmable logic controller (PLC) or distributed control system (DCS). Typically built into a ruggedized terminal for shop floor use, it provides a remote interface to the push buttons, switches and gauges found on the equipment itself. An OI does not offer the rich graphics and flexibility as do Windows and Mac-based interfaces. Contrast with HMI. See PAC, PLC and DCS.