Other
- Catalan Solidarity for Independence (SI or SCI), an independist Catalan political party
- Scalable Coherent Interface
- SCI 124, the notation for the Shapley Supercluster
- Sensitive Compartmented Information
- Serial Communication Interface
- Sierra's Creative Interpreter
- Site of Community Importance
- Smart Charge Injection
- Special Criminal Investigation, a video game
- Spinal cord injury
- String Cheese Incident, a jam band
- Structure Conservation Index
- Sci.*
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