| Abbreviation | Definition |
|---|---|
| SHWA | Samuel H Williamson Associates |
| SHWR | Steven Hale Watch Restoration |
| SI | Science Industrielle |
| SI | Southport Inn |
| SIAC | Southern Irish Asphalt Company |
| SIAD | Società Italiana Acetilene e Derivati, SPA |
| SIAI | Sportsman's Insurance Agency, Inc. |
| SIAM | Southen Indiana Antique Machinery |
| SIBC | Seaway International Bridge Corporation |
| SIBC | Shetland Islands Broadcasting Company |
| SIBC | Singapore Island Brewing Company |
| SIBC | Solomon Islands Broadcasting Corporation |
| SIBI | SunGard Institutional Brokerage Inc |
| SIC | Solutions Informatisees Corporatives |
| SIC | Stoves Incorporated |
| SICI | Speck Industrial Controls, Inc. |
| SICO | Surat IT Company Owners |
| SIDC | Seafood Industry Development Company |
| SIDC | Securities Industry Development Corporation |
| SIDC | Southern Illinois Dance Company |