| SI | System of Units | 国际量制 |
| SI | International System of Unit | 国际单位制 |
| SI | Sub-investigator | 助理研究者 |
| SI | System Integrators | 系统集成商 |
| SI | SLOVENIA | 斯洛文尼亚 |
| SI | Store Identity | 商店识别 |
| SI | sequential injection | 序列注射技术 |
| SI | Silicon | 硅(化学元素) |
| SI | Statutory Instrument | 有效立法 |
| SI | Service Indicator | 业务表示语 |
| SI | schedule index | 进度指数 |
| SI | silicone | 聚硅氧烷 |
| SI | Silicone plastics | 有机硅塑料 |
| SI | Shipping Instruction | 发货指令 |
| SI | System Information | 系统信息 |
| SI | Sound Installation | 音响设备 |
| SI | Sound Insulation | 隔音 |
| SI | Saline injection | 生理盐水注射 |
| SI | Saline infusion | 生理盐水灌注 |
| SI | Serum iron | 血清铁 |
| SI | Strategic Intent | 策略意向 |
| SI | Spark Ignition | 火花塞点火 |
| SI | Salt Institute | 盐业协会 |
| SI | Society for India (Cornell University) | 印度协会(康奈尔大学) |
| SI | Silicon Image, Inc | 矽映公司 |
| SI | Systems Intelligence (psychological theory) | 系统智能(心理学理论) |
| SI | Sacroiliac | 骶髂肌 |
| SI | Small Intestine | 小肠 |
| SI | Seriously Ill | 严重疾病 |
| SI | Self Inflicted | 自找的傷口 |
| SI | Special Intelligence | 特殊情报 |
| SI | Staten Island | 斯塔滕岛 |
| SI | System Integrator | 系统集成商 |
| SI | Self-Injury | 自我伤害 |
| SI | Shift In | 移入 |
| SI | Sergeant Instructor | 中士教官 |
| SI | Source Index | 源索引 |
| SI | Still Image | 静止图像 |
| SI | Side Information | 侧面信息 |
| SI | System International | 系统国际 |
| SI | Supplemental Instruction | 补充说明 |
| SI | Sexual Intercourse | 性交 |
| SI | Swarm Intelligence | Swarm智能 |
| SI | Suicidal Ideation | 自杀理想 |
| SI | Straight-In Approach | 直进进近 |
| SI | Secondary Injection | 二次喷射 |
| SI | Superimpose | 叠加 |
| SI | Scintillation Index | 闪烁指数 |
| SI | Specific Impulse (measure of efficiency of rocket engines) | 比冲(火箭发动机效率的测量) |
| SI | Strategic Investor | 战略投资者 |
| SI | Spokane International Railroad Company | 斯波坎国际铁路公司 |
| SI | Shrouded Isles (gaming, Dark Age of Camelot add-on) | 被遮蔽的岛屿(游戏,Camelot的黑暗时代附加组件) |
| SI | Sistema de Informação | Sistema de Informação |
| SI | Solution Implementation | 解决方案实施 |
| SI | Strategic Initiative (management) | 战略倡议(管理) |
| SI | Supporting Installation | 配套安装 |
| SI | Societatis Iesu, Latin for Society of Jesus, Jesuits (religious order) | Societatis Iesu,拉丁语代表耶稣会,耶稣会士(宗教秩序) |
| SI | Situationist International (governing body of political dissidents circa 1968) | 情境主义者国际(1968年左右的政治异议人士管理机构) |
| SI | Scalable Infrastructure | 可扩展的基础架构 |
| SI | Scientific Investigation | 科学调查 |
| SI | Smoothness Index | 平滑度指数 |
| SI | Service Information | 服务指南 |
| SI | Shadow Instruction (computer instruction set) | 影子指令(计算机指令集) |
| SI | Surveyor Intern | 测量师实习生 |
| SI | Service Index | 服务索引 |
| SI | School of Information (university) | 信息学院(大学) |
| SI | SPARC International, Inc. | SPARC国际公司。 |
| SI | Systems Integrator | 系统集成商 |
| SI | Standardization (Flight) Instructor | 标准化(飞行)教员 |
| SI | Schweizer Informatiker Gesellschaft (Zurich, Switzerland) | Schweizer Informatiker Gesellschaft(瑞士苏黎世) |
| SI | Safety/Site Inspection | 现场检查安全/ |
| SI | Surveillance Index | 监督指数 |
| SI | Software Item | 软件项 |
| SI | Site Inspection | 现场检查 |
| SI | Special Inspection | 特殊检查 |
| SI | Site Investigation | 现场调查 |
| SI | Swap-In | 换入(Swap In) |
| SI | System Interface | 系统接口 |
| SI | Scientific Instrument | 科学仪器 |
| SI | Supplementary Insulation | 补充绝缘层 |
| SI | Sucrase-Isomaltase Deficiency | 蔗糖酶异麦芽糖酶缺乏症 |
| SI | Shut-In | 关机 |
| SI | Simple Interest | 简单利息 |
| SI | Sensitivity Information | 敏感性信息 |
| SI | Sensory Integration | 感官整合 |
| SI | Saturation Index | 饱和度指数 |
| SI | Speech Impairment | 言语障碍 |
| SI | Serious Injury | 严重伤害 |
| SI | Soil Investigation | 土壤调查 |
| SI | Similarity Index | 相似性指数 |
| SI | Swine Influenza | 猪流感 |
| SI | Special Instruction | 特别说明 |
| SI | Signaling Intelligence | 信号智能 |
| SI | Sports Illustrated | 体育画报 |
| SI | Systems Integration | 系统集成 |
| SI | SystÈme International d'UnitÉs (international system of units based on the Meter, Kilogram, Second, Ampere, K | SystÈme International d'UnitÉs (international system of units based on the Meter, Kilogram, Second, Ampere, K |
| SI | Slovenia (international code) | 斯洛文尼亚(国际代码) |
| SI | Smithsonian Institution | 史密森学会 |
| SI | Signal Integrity | 信号完整性 |
| SI | sulfisoxazole | 硫异恶唑 |