| I&O | In and Out 
| Others |
| I&O | Infrastructure & Operations
| Others, Technology |
| I&O | Inlet And Outlet
| Hardware |
| I&O | input and output (fluid monitoring)
| Medical |
| I&O | input and output (fluid)
| Others |
| I/O | In-Port Operations
| Transport |
| I/O | Input/ Output
| Others |
| I/O | Input/Output
| Technology |
| I/O | Interest Only
| Finance |
| I/O | Intraosseous
| Medical |
| IO | CPIO Compressed file archive
| Others |
| IO | Identification Orders
| Others |
| IO | Illuminati Online
| Others |
| IO | Images Only
| Others |
| IO | Immediate Occupancy
| Others |
| IO | Immediate Office
| Others |
| IO | Immediate Outcomes
| Others |
| IO | Imperfect Obstructionist
| Others |
| IO | Imperial Order
| Others |
| IO | Imperial Outpost
| Others |
| IO | In Often
| Others |
| IO | In Order ....
| Others |
| IO | In Ordnung
| Others |
| IO | In Our
| Others |
| IO | Inboard Outboard
| Others |
| IO | INBOARD/ OUTBOARD
| Others |
| IO | Incoming Order
| Others |
| IO | India Office
| Others |
| IO | Indirect Object
| Others |
| IO | Industrial and Organizational
| Others |
| IO | Industrial Organizational
| Others |
| IO | Infinitely Often
| Others |
| IO | Information Objectives
| Others |
| IO | Information Officer
| Others |
| IO | Information Online
| Others |
| IO | Information Operation
| Others |
| IO | Information Operations
| Others |
| IO | Information Organization
| Others |
| IO | Initial Object
| Others |
| IO | Input and Output
| Others |
| IO | Input Output
| Others |
| IO | Inputs And Outputs
| Others |
| IO | Insatiable Ouroboros
| Others |
| IO | Insertion Order
| Others |
| IO | Inside Out
| Others |
| IO | Inside Outside
| Others |
| IO | Inside Outsider
| Others |
| IO | Inspection Opening
| Others |
| IO | Instance Of
| Others |
| IO | Instant Offense
| Others |
| IO | Institute Of
| Others |
| IO | Integration Objects
| Others |
| IO | Intellect Optional
| Others |
| IO | Intelligence Officer
| Others |
| IO | Intelligence Oversight
| Others |
| IO | Inter-Office
| Others |
| IO | Interacting Object
| Others |
| IO | Interaction Objects
| Others |
| IO | Interactive Optimum
| Others |
| IO | Intermediate Objective
| Others |
| IO | Intermittent Operation
| Others |
| IO | Internal Oblique
| Others |
| IO | International Oddities
| Others |
| IO | International Office
| Others |
| IO | International Officer
| Others |
| IO | International Organization
| Others |
| IO | Internet Officer
| Others |
| IO | Internex Online
| Others |
| IO | Interpolate Once
| Others |
| IO | Intestinal Obstruction
| Others |
| IO | Into the Outdoors
| Others |
| IO | Investigating Officer
| Others |
| IO | Investor Optimum
| Others |
| IO | IO Inferior oblique (of eye)
| Others |
| IO | Iowa old
| Others |
| IO | Object file (Modula-3)
| Others |
| IO | The Intensity Of
| Others |
| I\O | Input\Output
| Others |