| IO | Integrated optics | 集成光学 |
| IO | Information Outlet | 信息插座 |
| IO | Image Orthicon | 超正析象管 |
| IO | Indian Ocean | 印度洋 |
| IO | Interpretive Operation | 翻译操作 |
| IO | In Organization (banking) | 组织内（银行） |
| IO | Information Outlet (LAN) | 信息插座（LAN） |
| IO | Intermon Oxfam (Spain) | 国际乐施会（西班牙） |
| IO | Imperial Order (gaming) | 帝国秩序（游戏） |
| IO | Inventory Objective | 库存目标 |
| IO | Indian Orchard (Springfield, MA) | 印度果园（马萨诸塞州斯普林菲尔德） |
| IO | Intelligence Oversight | 情报监督 |
| IO | Instant Outlining | 即时大纲显示 |
| IO | InspecciÒn Ocular (Guatemala, police task force) | InspecciÒn Ocular (Guatemala, police task force) |
| IO | Industrial-Organizational (Psychology) | 工业组织（心理学） |
| IO | Initial Only | 仅首字母 |
| IO | Installing Officer (International Order of DeMolay) | 安装官（DeMolay国际订单） |
| IO | iodine monoxide | 一氧化碘 |
| IO | Independent Observations | 独立观察结果 |
| IO | Individually Optimum | 个人最佳 |
| IO | Inside Out (Frisbee throw) | 里外（飞盘投掷） |
| IO | Inspectie van het Onderwijs (Dutch) | 检查van het Onderwijs（荷兰语） |
| IO | Inboard Outboard (boat drive system) | 内侧外侧（船驱动系统） |
| IO | Insignificant Other | 无关紧要的其他 |
| IO | Inexperienced Operator | 经验不足的操作员 |
| IO | Idiot Operator | 白痴操作员 |
| IO | Imperfect Obstructionist | 不完全阻碍者 |
| IO | Instance Of | 的实例 |
| IO | Interactive Optimum | 交互式优化 |
| IO | Information Operation | 信息操作 |
| IO | Intellect Optional | 智能可选 |
| IO | Inboard Outboard | 内侧外侧 |
| IO | Images Only | 仅图像 |
| IO | Identification Orders | 身份识别订单 |
| IO | CPIO Compressed file archive | CPIO压缩文件归档 |
| IO | Internet Officer | 互联网官员 |
| IO | Interpolate Once | 插值一次 |
| IO | In Ordnung | 在Ordnung |
| IO | In Our | 在我们的 |
| IO | Imperial Outpost | 帝国前哨 |
| IO | Interacting Object | 交互对象 |
| IO | In Often | In经常 |
| IO | Inside Outside | 内部-外部 |
| IO | Object file (Modula-3) | 对象文件（模块-3） |
| IO | Inter-Office | 内部办公室 |
| IO | Information Online | 在线信息 |
| IO | International Officer | 国际官员 |
| IO | Intermediate Objective | 中间目标 |
| IO | International Organization | 国际组织 |
| IO | Intelligence Officer | 情报官员 |
| IO | Information Overload | 信息过载 |
| IO | Indirect Object | 间接对象 |
| IO | Intraosseous | 骨内的 |
| IO | Industrial Operations | 工业运营 |
| IO | Immigration Officer | 入境事务主任 |
| IO | Information Object | 信息对象 |
| IO | Input Operator | 输入运算符 |
| IO | If Only | 要是…就好了 |
| IO | Information Officer | 信息军官 |
| IO | Internal Order | 内部订单 |
| IO | Internal Organ | 内部器官 |
| IO | Immediate Office | 直属办公室 |
| IO | Interactive Optimum (cable services) | 交互式优化（有线服务） |
| IO | Ionium (Thorium Isotope) | 离子（钍同位素） |
| IO | incisal opening | 切迹开口 |
| IO | internal os(cervix) | 内os（宫颈） |
| IO | ionium | 离子 |
| IO | inferior oblique(eye muscle) | 下斜肌（眼肌） |
| IO | inside-out(vesicle) | 由内向外（囊泡） |
| IO | inferior olive | 劣质橄榄油 |
| IO | intraocular | 眼内的 |
| IO | infraorbital | 轨道下的 |
| IO | Input/ Output, Inc. | 输入/输出的公司 |
| IO | Investigating Officer | 调查官员 |
| IO | Internex Online | Internetx在线 |
| IO | Information Organization | 信息组织 |
| IO | Incoming Order | 传入订单 |
| IO | Initial Object | 初始对象 |
| IO | Imperial Order | 帝国秩序 |
| IO | In Order .... | 整齐 |
| IO | Intermittent Operation | 间歇性操作 |
| IO | Inside Outsider | 内部-外部 |
| IO | INBOARD/ OUTBOARD | 内/舷外 |
| IO | Instant Offense | 即时进攻 |
| IO | Iowa (old style) | 爱荷华州（老式） |
| IO | Information Output | 信息输出 |
| IO | Information Operations | 信息作战 |
| IO | Intestinal Obstruction | 肠梗阻 |
| IO | Infinitely Often | 无限频繁 |
| IO | Institute of Oceanography | 海洋研究所 |
| IO | Illuminati Online | 照明在线 |
| IO | Insertion Order (web advertising) | 插入顺序（网络广告） |
| IO | Isomerized Olefin | 异构化烯烃 |
| IO | Interoperability Objective | 互操作性目标 |
| IO | Information Orientation | 信息导向 |
| IO | InvestOne (software) | InvestOne（软件） |
| IO | Infrastructure Optimization | 基础设施优化 |
| IO | Interest Only | 仅限利息 |