| Abbreviation | Definition |
|---|---|
| SIF | Societ Italiana di Fisica |
| SIF | Società Italiana di Fisica |
| SIFD | Society for International Folk Dancing |
| SIFFS | Sensory Impaired Family Friends Society |
| SIFFS | South India Federation of Fishermen Societies |
| SIFFS | South Indian Federation of Fisherman Societies |
| SIFS | Southern Illinois Flute Society |
| SIGEVO | Special Interest Group for Genetic and Evolutionary Computation [of the Association for Computing Machinery (ACM)] |
| SIGMA | Society Of Independent Gasoline Marketers Of America |
| SIGRAD | Svenska Föreningen för Grafisk Databehandling |
| SIGRAD | Svenska Freningen fr Grafisk Databehandling |
| SIGRAD | Swedish Computer Graphics Association |
| SIGRAV | Italian Society of General Relativity and Physics of Gravitation |
| SIGRAV | Societ Italiana di Relativit Generale e Fisica della Gravitazione |
| SIGRAV | Società Italiana di Relatività Generale e Fisica della Gravitazione |
| SIGU | Italian Society of Human Genetics |
| SIGU | Societ Italiana di Genetica Umana |
| SIGU | Società Italiana di Genetica Umana |
| SIL | Association of Electrical Engineers (Finland) |
| SIL | International Association of Theoretical and Applied Limnology |