| System International | Academic & Science |
| Système International d‘unités | Academic & Science |
| Student Instructor | Academic & Science |
| Smithsonian Institute | Academic & Science |
| Scientific Instrumentation | Academic & Science |
| St. Ignatius College Preparatory | Academic & Science |
| Silay Institute | Academic & Science |
| Seed Implantation | Academic & Science |
| Student Improvement | Academic & Science |
| Société Suisse des Informaticiens | Academic & Science |
| Società Svizzera degli Informatici | Academic & Science |
| Swiss Informaticians Society | Academic & Science |
| Schweizer Informatiker Gesellschaft | Academic & Science |
| Society of Indexers | Academic & Science |
| Icelandic Society for Information | Academic & Science |
| Skýrslutæknifélag Íslands | Academic & Science |
| Système International d'unités (International System of Units) | Academic & Science |
| Slightly Insane | Academic & Science |
| Schweizer Informatik Gesellschaft | Associations & Organizations |
| Survival International | Associations & Organizations |
| Samahang Ilokano | Associations & Organizations |
| Standing Instruction | Banking |
| Simple Interest | Business |
| Secondary Insurance | Business |
| Soft Intermediate | Business |
| Salt Institute | Business |
| ACM Government Spectrum Fund, Inc. | Business |
| Software Independent | Business |
| Solution Integration | Business |
| System Integrator | Business |
| Seller Identification | Business |
| Southport Inn | Business |
| Science Industrielle | Business |
| Syst | Chemistry |
| Stability Index | Chemistry |
| Saturation Index | Chemistry |
| Silicon | Chemistry |
| Sports Illustrated | Community |
| Stark Industries | Community |
| Sultan Ismail | Community |
| Speech/Language Impairment | Community |
| Stand-In | Community |
| Small Inclusion | Community |
| Social Infrastructure | Community |
| SAS Institute | Community |
| School of Information | Community |
| Side Information | Community |
| Signaling Intelligence | Computer and Networking |
| Still Image | Computer and Networking |
| Signed Integer | Computer Assembly Language |
| Source Index | Computer Assembly Language |
| Small Interface | Computer Hardware |
| Socket Interface | Computer Hardware |
| Secure Internet | Computing |
| Slovenia (TLD) | Computing |
| Solutions Infini | Computing |
| Swarm Intelligence | Computing |
| Sub Indices | Computing |
| Shift In | Computing |
| Single Inheritance | Computing |
| Standard Interface | Computing |
| Semi Iterative | Computing |
| Slovenia | Country Names |
| Siberian Islands | Country Specific |
| Siren | Cryptocurrency |
| Signal Integrity | Electronics |
| Semi-insulating | Electronics |
| Softimage Graphics | File Type |
| Stochastic Interest | General |
| SI is | General |
| Standing Instructions | General |
| Sine Integral | General |
| Standard Image | General |
| Social Issues | General |
| stand for Incorrect | General |
| Self Indulgent | General |
| Spark Ignition | General |
| Self Insert | General |
| Speaker Independent | General |
| Space Invaders | General |
| Shitty Intuition | General |
| Stereo Input | General |
| Supplementary Instruction | General |
| Stupid Investigators | General |
| Seller Id | General |
| Shahrizat Ismail | General |
| Self Indulgance | General |
| Sporty Intellect | General |
| Substitution Instance | General |
| Slow and Ignorant | General |
| Self Instertiong | General |
| Super Insulation | General |
| Signed Integers | General |
| Slightly Imperfect | General |
| Safety Index | General |
| Silicone | General |
| Self Injure | General |
| Standard International | General |
| Sensory Imagery | General |
| Sensory Imageryre | General |
| Systems Integrated | General |
| Structural Injunction | General |
| System Integrators | General |
| Systems Integral | General |
| String Instrument | General |
| Statutory Instrument | General |
| Summer Intensive | General |
| Silicon Investor | General |
| Sporrs Ideas | General |
| Stuck Ina | General |
| Sexually Inactive | General |
| Something In | General |
| Stand for in | General |
| s for in | General |
| SiR in | General |
| Safe Intake | General |
| s for International | General |
| Slovenia international | General |
| Slight Inclusions | General |
| Système International | General |
| Silicon in | General |
| Southern Islands | General |
| Stand for Ie | General |
| Slightly Included | General |
| Snow and ice | General |
| Svenska Institutet | Governmental |
| Solidaritat Catalana per la Independència | Governmental |
| Socialist International | Governmental |
| Solidaridad e Igualdad | Governmental |
| Side Impact | Governmental |
| Secure Investment | Governmental |
| Sub Inspecter | Governmental |
| Site Investigation | Governmental |
| Systeme Internationale | Governmental |
| Special Investigations | Governmental |
| Sequential Injection | Governmental |
| International System | Governmental |
| Staten Island | Governmental |
| SCI Corporation | Governmental |
| Station Inspector | Governmental |
| Smoke Inhalation | Governmental |
| Sub-Inspector | Governmental |
| Supplemental Instruction | Governmental |
| Special Inquiry | Governmental |
| Sub-Inspector of Police | Indian Police Rank |
| SONALLI | Indian Railway Station |
| Siena (Provence) | International |
| Sarekat Islam | International |
| Servicio de Investigación | International |
| Stupid Idiot | Internet |
| Stop It | Internet |
| Sumatra Interactive | Internet |
| Special Investigator | Jobs |
| The International System of Units | Maths |
| Self Inserted | Medical |
| Suicidal Ideation | Medical |
| Saline Injection | Medical |
| Speech Impaired | Medical |
| SacroIliac | Medical |
| Self Inflicted | Medical |
| Self Insertion | Medical |
| Substantia Innominata | Medical |
| Small Intestine | Medical |
| Sagittal Index | Medical |
| Saline Infusion | Medical |
| Satiety Index | Medical |
| Secondary Infertility | Medical |
| Sensitivity Index | Medical |
| Serious Illness | Medical |
| Serious Injury | Medical |
| Seriously Ill | Medical |
| Serum Iron | Medical |
| Severity Index | Medical |
| Sexual Intercourse | Medical |
| Sexually Inexperienced | Medical |
| Shock Index | Medical |
| Signal Intensity | Medical |
| Silent Infarction | Medical |
| Silent Ischaemia | Medical |
| Singh Index | Medical |
| Sinus Irregularities | Medical |
| Situs Inversus | Medical |
| Smoking Index | Medical |
| Snoring Index | Medical |
| Social Interaction | Medical |
| Spinal Injury | Medical |
| Stratum Intermedium | Medical |
| Stress Incontinence | Medical |
| Stroke Index | Medical |
| Structured Interview | Medical |
| Superior/Inferior | Medical |
| Survival Index | Medical |
| Systolic Index | Medical |
| Self Injury | Medical |
| Simply Irresistible | Messaging |
| Silly I | Messaging |
| Special Intelligence | Military and Defence |
| Support Installation | Military and Defence |
| System Integration | Military and Defence |
| Special Interest | Military and Defence |
| United States Strategic Command Strategic Instruction | Military and Defence |
| Selectable Interface | Networking |
| Slow Import | Networking |
| Selectivity Index | Physics Related |
| Slight Inclusion | Physics Related |
| Sino Indian | Regional |
| Spokane International Railroad (Union Pacific Railroad) | Regional |
| Singhalese | Regional |
| Sandwich Islands | Regional |
| Union Pacific Railroad Company | Regional |
| Smithsonian Institution | Regional |
| Societas Iesu | Society & Culture |
| Kennedy Space Center Support Operations Directorate | Space Science |
| International Systems of Units (isu Preferred) | Space Science |
| Scientific Instrument | Space Science |
| Solar Inertial | Space Science |
| Sport Injected | Sports |
| Sport Influenced | Sports |
| Sanctioned Individual | Sports |
| Sports Injection | Sports |
| Sports Information | Sports |
| Sports Injected | Sports |
| Sport Ident | Sports |
| Sport Injection | Sports |
| Sports Interactive | Sports |
| Stockmarket Indices | Stock Exchange |
| Province of Siena | Transport & Travel |
| Skynet Airlines | Transport & Travel |
| Spokane International Railroad | Transport & Travel |
